Definitions by DKD
SWAG
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.
covering
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.