This command opens up your Documents folder, a very important folder indeed. It's designed to store just about all the work you do on your PCeverything except Music, Pictures, and Videos, which get folders of their own.
Of course, you're welcome to file your documents anywhere on the hard drive, but most programs propose the Documents folder as the target location for newly created documents.
Sticking with that principle makes a lot of sense, because it makes navigation easy. You never have to wonder where you filed something, since all your stuff is sitting right there in Documents.
Documents 