The arrangement of Black’s king and knight seems almost perfect for a rook fork: a king and a loose piece on the same rank with nothing between them always should set off an alarm, and here White has a rook at the ready on e1. The problem is that the Black king guards the forking square, e7, and White has no way to add protection to that square that is safe and holds the initiative. Time to give up? No; time to imagine playing the fork anyway and asking what would be possible if it fails. Thus 1. Re7+, KxR; and now Black’s king has moved, requiring a fresh look at the resulting position. The king’s move would have left the bishop on g6 loose; plus the king would be on e7, a dark square; and the rook at h8 would be on a dark square as well. White has a knight in the vicinity, and on a dark square. You get the picture: 2. NxB+ is a knight fork that takes the bishop right away and wins back the rook next move. White gains a piece with the sequence.
This position illustrates a valuable instinct to develop. The mind recoils initially at the thought of Re7+ because it loses the rook; the natural temptation is to abandon the idea and search for something safer. Cultivate the opposite habit of mind: a willingness to persist, imagining the loss of the rook and looking for what would then be possible on the board.