1. a sudden and unexpected piece of good fortune or an advantage that you gain, or an amount of money that you win or receive unexpectedly
  2. fruit blown down by the wind (this meaning probably makes the word clearer)

In the picture:

With his lottery WINDFALL he will live more comfortably. (Sa novcem koji mu je pao sa neba kad je dobio na lutriji živeće mnogo komfornije.)