Look at the Black king’s position and you see a pin of the bishop on e8 by White’s rook, but no way to take advantage of it since it is guarded once and there is no immediate way to call in another attacker against it. So again: initiate an exchange with the pinning piece. Imagine 1. RxB, QxR, and now a renewed scan of the Black king and its lines, and of White’s offensive resources, turns up a new pin to impose: Re8, paralyzing the queen and winning it next move. Since the queen is being pinned White needs protection for his rook, and gets it from the bishop on h4.

This sequence is the payoff of the fine coordination of White’s pieces. He effectively starts with three of them all trained on (or occupying) d8; he owns that square, and now you see one of the possibilities such ownership can create. Pieces can attack from there and then can be replaced by the other pieces that backed them up.