It's good practice to pay attention to lines leading toward the enemy king, and to see in a case like this that White has a bishop bearing down on the diagonal where Black’s king sits—and that the bishop is masked by the pawn on d5. If the pawn could advance to d6, the unmasked bishop would give check and the pawn would take Black’s queen a move later. The challenge is to get rid of the bishop on d6 that blocks the pawn’s progress. How? By capturing something it guards, naturally. One thing it protects is the rook on e7. White can take it with QxR. After Black recaptures BxQ, White is free to move his pawn to d6 and win back his queen after Black moves his king. White nets a rook.