'if you dont know what it means why the hell are you using it...' Geekspeak at its worse...
Well, unfortunately, that's the very point with Java ....
If you were using a website that required you to run a java applet, you'd probably know about it.
If you were using a locally installed java software application.... you'd probably already know about it.
Hence .... if you don't know what it is or what you need it for, you are unlikely to have any use for it.
Uninstalling Java won't do you any harm. If you find some software or website breaks after you've uninstalled it, you can easily reinstall it.
There are quite a few things in my computer folders they I have no idea what they do. The computer seems to work albeit slow sometimes.
I guess the best way to find out what's really important is to start deleting stuff that my update screen says it needs updating. That way I can tell afterwards what was really important when stuff doesn't work at all and the screen turns blue from the cold.