Cover version - Wikipedia: "In popular music, a cover version or cover song, or simply cover, is a new performance or recording of a contemporary or previously recorded, commercially"
He's covering Ed Sheeran.
It has been traced back to 1640, where it's used to refer to "hansom swag fellowes." It refers to stylish confidence. It is a derivative of the word "swagger
", (rather than the "swag" that is a reference to free loot, and this use is NOT an acronym for any words.) It refers to a confident attitude or manner.
"Not only is he handsome, he's got swag