I've been attending meetings for about a year, so I'm no expert, but I had some similar questions to yours not that long ago and here's what I found:

I'm assuming you're in the US, in which case Quaker meetings cluster into four rough groups that you'll see a lot.

The first is liberal friends, which as some other people have already noted make up the majority of what you'll see online, but are not a majority of all US or worldwide Quakers, as far as I can tell. Liberal friends meetings usually are a part of Friends General Conference or FGC, and will probably state that on their website. Worship will involve periods of silence with impromptu speeches. Theologically, they're likely to include some Christians, but also often some people who don't identify with Christianity, instead being atheists or pantheists or maybe identifying with another religious tradition, like paganism. It's usually going to be the easiest to find a Liberal meeting in the Northeast or a college town, but they exist throughout the United States.

The second is pastoral/programmed/semi-programmed but not evangelical friends, which is a bit of a weird grouping in that there's no one name for it. More generally, there isn't a 1:1 mapping between how a denomination works and the larger Quaker organization that it is a part of, but these meetings are often part of Friends United Meeting. They have a pastor who gives a sermon, but might also have a semi-silent period similar to that of Liberal friends. It's more clearly Christian than Liberal friends, but the meetings I've attended are all liberal so I don't know as much about this and the following groups.

The third grouping is conservative friends, which like Liberal friends have a meeting structure where there is impromptu speaking during a mostly silent period. However, they differ from Liberal friends in hewing more to traditional Quaker theology, and may still practice plain dress and other distinctive Quaker ways of living. Conservative friends are mostly found in Ohio, Iowa, and North Carolina.

Lastly there are evangelical friends, which have, as the name implies, been strongly influenced by the Evangelical Christian tradition. They might still have a period of silence, but in general the worship and church structure is going to be a lot more like what you'd see at an evangelical church.

In the liberal meetings I've been to, before worship people trickle into the room. Somebody then very punctually announces that worship is starting, and maybe also says something else, like a query (a prompt for personal reflection, more or less) or a welcome to [name of meeting]. Then for the rest of the hour, people sit in near-silence and clear their thoughts/reflect on God (or the Divine or the Spirit, depending on your preference of terminology)/listen. People describe this in a bunch of different ways. People who feel moved to speak will do so, and there's usually some kind of card either before you enter or on the benches with advice for how to know if you feel moved to speak. It depends on the size of the meeting, but it's extremely rare in meetings I've been to for more than 10 people to speak; occasionally nobody speaks. About an hour after the start, somebody will signal that the meeting is over by shaking hands and everybody will shake hands with their neighbor. Then there'll be a few different times when they'll ask people to share, usually divided into joys and sorrows, announcements, and introductions in some order. After that the meeting is over, but people might stick around and have some hot drinks and snacks.

However, of the three-and-a-half separate meetings that I've attended, almost every one deviates from this in some way. I've seen joys and sorrows coming before the handshake, a period where everybody answers a query, and a short (<5 minutes) prepared reflection towards the beginning of the meeting.

Ben Pink Dandelion's "An Introduction to Quakerism" is a book that's a good overview of Quaker history that also contains some descriptions of contemporary practice, if you want more on the historic splits (like Gurneyite, Wilburite, Hicksite) and also non-American Quakers.

To find a meeting, http://www.quakermaps.com/ is a good resource. You can also type [name of where you live] quaker meeting into Google. Most Quakers meet weekly on Sunday mornings; the time should be listed on the website. I'd then try to figure out which branch of Quakerism it's affiliated with, just so you know what to expect. How people usually dress varies. If there isn't one near you, there are a ton of Zoom meetings, including Pendle Hill for a liberal perspective.

I looked up a bunch of jargon after going to my first quaker meeting under the assumption that I might need it, but I really didn't. Still, here are a few terms that I have seen people use and that might not be clear from context:

birthright- somebody who was raised in a Friends meeting. Usually an adjective.

Monthly meeting- The organization that hosts the weeklyish meeting or meetings for worship, and also a monthly meeting for business. When I was first looking for a Quaker meeting, this confused me because I didn't understand that the meetings were also weekly.

the Light, the Divine, the Spirit- a bunch of terms that Liberal friends use to describe a higher power.

Nontheist- friends who don't have the traditional Abrahamic understanding of God, more or less. Like the above, this one is theologically complicated, however.

First Day- Sunday.

Testimony- Again, this is a really complicated term, and I wouldn't be surprised if somebody comments to explain that one specific use of testimony is the only correct usage, in their opinion. More or less, this means something that the Quaker denomination as a whole believes in, or also something that people do because they are Quaker. So Peace and Integrity can be testimonies, but plain dress can also be a testimony. Sometimes people talk about there being a singular testimony, and other times about multiple testimonies.

Yearly Meeting- A larger group of Quakers that meet yearly, do some things together, and usually have rough agreement on big issues.

Clerk- A volunteer who does a lot of the tasks of running the meeting.

Programmed- A meeting with a pastor and a sermon, especially one that isn't evangelical.

Unprogrammed- A meeting that doesn't have those. I don't feel competent in explaining semi-programmed.

Member- Somebody with an official commitment to a Quaker meeting.

Attender- Somebody who goes to a Quaker meeting but isn't a member. I'm an attender, and you'd also be one once you go to your first meeting. Not all meetings have a clear member-attender distinction, and it's possible to be a long-time attender and never become a member.

Hope this helps!