To impart a spin to something in an effort to make it hard to control, usually a ball in sports like tennis.
Your serve is dangerous when you put English on it.
The English way or English comes from the British game of Snooker. Snooker is a forerunner to the game of Billiards or pool. Similar to pool, Snooker uses cue sticks, balls, and a table however the table has no pockets.
A technique used in Snooker is to impart a spin to the ball to alter its travel.