White has a bishop with a rook—indeed, two rooks—behind it on the same file. The arrangement signals the possibility of a discovered attack. White has a fine target for the rooks on c8. True, the rook there is protected by Black’s other rook at f8; but since White has two rooks trained on the square, the target is attacked twice and protected only once and so is as good as loose. White looks for a check or other violent move to give with the bishop, and plays Bxf7+. However Black responds to this check, White next plays RxR and wins the exchange.