If the ball is kicked to make it spin around an axis that is close to perpendicular to the ground. One side of the ball will be spinning into the direction of flight and the over side will be spinning away from the direction of flight. This produces an imbalance in the lateral forces on the ball -- This is usually called the Magnus Effect, although this is not quite correct. When the ball travels through a fluid (like air), the fluid is pushed out of the way like a when a boat travels through water. The fluid pushes on the object moving through it. If the object spins while in motion the fluid moves around the object in an asymmetric pattern.