Since MS bought it, aren't there two versions, a legacy one called "Java" and the newer one from MS, probably not in Java and with all the cool kids (multiplayer mode) on it?

There is Java and bedrock. Everyone I know has Java. There are other differences, but multiplayer is available in both.

The difference it's that bedrock allows you to play with the people that use Minecraft on consoles or mobile and Java doesn't

Another key difference is that Java has mods and shaders, bedrock doesn't.

Mojang is trying to fix this with resource and data packs, but even still, those are not full powered mods.

You're right, my bad!

I remembered some friends complaining about the fact the since MS, they couldn't play as they did before because of two versions co-existing