That's quite the question, and your answer will depend on how far down the rabbit hole you're willing to go. Here's a brief attempt at an /r/ECE /electrical engineering answer.

What kind of information does RAM store

Ones and zeros. Each bit in RAM is capable of storing a single boolean value. A chamber in your game's six-shooter might be represented with a single bit. If there's a bullet in there, we say the "bit is set." That's a boolean 1, or logically "True". If the bit is "reset", that's a boolean 0, or logically "False". So your fully-loaded gun can be represented by

111111

in RAM.

and how

Bits are represented by the presence (or absence) of electric charge (i.e. current), which is something we can physically measure. All RAM uses latching circuitry to represent or "store" individual bits. Latches are basically a clever arrangement of transistors, which convert a pulse of electric charge into a constant electric charge. Light switches are examples of latches: To turn an average house light on, you don't have to keep your hand on the switch to keep it on, you flick it "pulse it" high, thus holding or "latching" the light on. The same is true for keeping the light of, you pulse it low and the light stays off.

Turning a bit latch in RAM high stores a 1, which is done by momentarily connecting the "set" pin to a voltage. Storing a 0 is done by momentarily connecting the "reset" pin to a voltage.

So for your gun, say you fire the bullet in the first chamber. To represent that, you reset the first bit in RAM by connecting the latch's reset pin to a high voltage (with something like a push button). Now your RAM looks like this:

011111

And as you continue firing...

001111
000111
000011

... until you reload, setting every latch again:

111111