is referred to the fans of the boy-band, SHINee.
The "sha" part stands for "SHINee"
The "wol" part stands for "world"
So in essence, Shawol = SHINee World. And it describes a fan of SHINee.
> Person: Hey, you're a fan of SHINee right?
> Fangirl: HECK YEAH!
> Person: So then are you a Shawol?
> Fangirl: OH YEAH~! I'm a crazy Shawol.