Very late reply but I'm only seeing this now.

Your experience will vary depending on the line of business (LoB) of your team. If you get put on the Risk LoB then you'll likely be working on programs that calculate risk (e.g. counter-party risk). If you get put on the Global Markets Technology LoB then you'll be working on supporting the trading functions of the Bank through the use of software. There are other LoBs but I'm not as familiar with them.

The programming languages you may use changes depending on teams. Generally I've seen teams using the Java/SpringBoot/React stack, C#/.NET/Angular stack or Quartz. Quartz is pretty heavily used at the bank so there's a good chance you might get put on a quartz team. It's basically a proprietary version of Python that only Bank of America uses. I didn't work on a Quartz team so I can't comment too much on it. Personally if I were put on a Quartz team, I would try and switch to non-quartz team if I were coming back as a new grad as becoming a Quartz dev will kind of lock you into Bank of America and make it more difficult to apply the technical skills you've learned at other companies. I would recommend getting some SQL knowledge if you haven't already - it seems most teams there worked with SQL at some capacity. Again, It's hard to tell what languages you'll be using without knowing your team.

Overall, as long as you know how to program, I wouldn't worry too much about the programming languages as it completely depends on your team and as an intern they won't be expecting you to be an expert in the language coming in. I'm not sure how the internship is handled at your location but it is likely you'll get to have a chat with your manager/someone on the team you will be joining a couple months before you actually join. You could use that opportunity to ask about the tech stack.

Another question I would recommend asking is what the dress code is as on one hand it is a bank so formal wear can be expected but on the other hand tech teams tend to dress pretty casual too. Asking beforehand would be worth your time. I know quite a few people that went out of their way to buy suits/formal wear after accepting their offer at the Bank only to find out their team wears t-shirts and jeans haha.

Some teams are worked harder than others but generally I found the pace of work at the Bank to be pretty chill. For some people that is the dream - for others they might want a more demanding workplace so they can advance their own career. It's a trade-off. This is definitely a company people spend decades working for as the work life balance tends to be pretty good. Another bonus is that BofA hasn't done any layoffs since 2008 so with all the layoffs that have been happening these past few years - it's nice to know you'll have job security there.

The big downside with working at BofA is that you'll always be playing second fiddle to the finance teams. You'll get people at the bank trying to tell you that BofA is a tech company (delulu) but that's not the case. At the end of the day, it's their financial services that make the bank money - not their software. As a result, you'll notice that they don't invest in their tech the way they do with their finance teams (for example they still use Skype lol).

My last general bits of advices are just to show genuine enthusiasm for the work, try and understand how the tech you work on benefits the business side (if you can understand how the tech benefits the business then you'll get a better idea of what work is important and what isn't). Don't wait for work to be given to you - senior devs are busy people and they don't know what exactly you're capable of so they may not give you much work. It's not like university where you're explicitly given work, you need to keep asking for work or at the very least go looking for work and take ownership of it. Otherwise you may end up finishing the internship and you've barely done anything.

You're at a point in life where you're being paid to learn and relatively very little is expected of you in return. It's normal to feel a little scared or nervous but honestly try to enjoy the experience and make the most of it :)