Sometimes you can't capture a piece to remove a defender, but you can distract that piece. Deflection is the tactic of removing a defender by making it move to another square. Often this involves a sacrifice that will be worth it for checkmate or greater material gains.
Black's rooks are in trouble - can you use a deflection tactic to save one rook and then bring the other rook to safety?
Black tries to deflect White's rook from the back rank, allowing checkmate. White should move the rook to safety on the first rank, allowing Black to save the rook on c8 with a powerful position.