Decoy is a tactic where you force a piece to a square that it doesn't want to be on. This can be used to remove a defender, lure a piece into a fork or even lure a king into checkmate.
Both sides are putting pressure on the kingside. Black is ready to capture the f2 pawn with the queen, but White has a decoy tactic that will win Black's queen. Find the move!
Nicely spotted! Black's king is decoyed to a forking square - win Black's queen!
White's decoy tactic wins Black's queen.