White’s immediate problem is that his queen is attacked by Black’s bishop. White looks at the attacking possibilities he has available and sees two principal candidates: QxBd5, which doesn’t much help as Black replies QxQ; and RxBe7, which is more interesting because the rook then attacks Black’s queen, creating a reciprocal threat to offset the threat Black has pending—a hostage. True, Black can play QxR, momentarily winning the exchange; but then White safely plays QxB+ after all (almost a good queen fork, but the rook on a8 has protection). Notice the visual relationships here. Black’s queen provides the only protection for both of his bishops. Since both bishops are under attack by White, one of them has to give. Again, the usual and obvious maxim is to start by making the capture that uses the less valuable of your two attackers—here, the rook.
If you find that your queen is attacked, remember that the attacker usually must have protection; so take a moment to ask whether its guardian has other responsibilities as well.