Complex sentence: The ball is "served" by one player standing in the service zone, by dropping the ball to the floor of the service zone and striking it on the bounce with the hand or fist so that it hits the front wall.
Split into simpler sentences: The ball is "served" by one player standing in the service zone. The server begins by dropping the ball to the floor of the service zone and striking it on the bounce with the hand or fist so that it hits the front wall.