Definition
Used to express unconcern.
Also Said As
How People Actually Use It
A polite way of saying it's okay, usually in a cool/caring manner.
"Person A: I am really sorry, but I spilled some soda on your girlfriends gym bag. Person B: Dude, it's all good. Don't sweat it because we will just use some stain remover to remove any stains on the bag or my girlfriend will just get over it. She needs a new gym bag anyway."
Source: Urban Dictionary