The parent comment is correct -- "offering a pawn" means allowing the other player to capture a pawn without yourself having an immediate way to regain it, usually banking on some kind of other piece activity as compensation for the material.
On move 9 it is a simple exchange of pawns and since the material remains equal after the resulting sequence of exchanges we would not refer to that as offering a pawn.
On move 9 it is a simple exchange of pawns and since the material remains equal after the resulting sequence of exchanges we would not refer to that as offering a pawn.