hmm wat does this exactly do? is IceWM another linux?

A window manager is a program that manages the windows of graphical applications - basically it is the desktop you see.

If you installed Ubuntu, then you ended up with a window manager called Gnome. (Actually, Gnome is a lot more, than just a window manager, but we'll keep things simple ) Gnome is the thing that shows you the login prompt, the fancy loading screen, the desktop, the panels and window decorations.

Unlike inferior operating systems (Windows), the OS itself, the graphics system and the desktop are completely separate and relatively independent in Unix and similar. The beauty of this is, that you can get rid of Gnome and use some other window manager (maybe not as pretty or streamlined, but a lot faster) instead without affecting any of your programs - they will display just the same, only with different window frames around them.

Hmm do you know how i can get rid on gnome?