Need Brief "Linux" Clarification, Please

Hey all...I'm looking at the possibility of purchasing a used/2nd-hand computer (PC or Mac, not sure - I really have little-to-no Mac experience), and I was hoping someone could explain this to me.

I hear about Linux all the time, but no clue what it would mean to an end-user (isn't it "Lucy's" little bro ... in "Charlie Brown's" world? hah~!).

The machine in question is a
Sony VAIO Notebook - 14 inch (VPCCW21FX/W) :

" . . . Used to have Windows 7 home on it, but I removed it and installed Ubuntu Linux. But the laptop has Original Windows 7 home product code underneath which can be used if you can get hold of a Windows CD".

 

Keep Windows, and use Ubuntu Windows Loader or WUBI. Allows you to choose to boot into Linux, or Windows 7, and that way you have both.

 

OK, thanks...I think I understand.