White’s knight masks his queen. The knight is not on the same color square as Black’s king, so it won’t be able to give check; and the queen’s natural target, the rook on e8, has protection. So study the knight’s circle of moves and ask what other offensive blows it might be able to strike. Its most interesting move is 1. NxB, a capture that threatens Black’s queen. Consider each of Black’s possible responses and then White’s replies. If 1. ...RxN, then now the rook on e8 is loose and White plays QxR. If Black instead plays 1. ...RxQ, White has NxQ+. Either way White gains an edge in material.