According to the Chess Tactics Guide, a deflection is "a cunning kind of decoy tactic used in the build-up to a main assault, where your opponent has a piece guarding a square or region of the Chess Board that would give you great attacking potential."
Use the deflection carefully, as it may cost you the game if you sacrifice a piece without calculating the best moves your opponent can make.
Here is a beautiful game:
Good luck with your chess!