Break means to separate into two or more pieces which can't be possibly reversed for fixing. It can also mean a short time observed for rest after working for hours.
A. "The Boss has permitted us to go for a five minutes break."
B. "I knew you broke the plates young man."
Brake is an equipment used to stop, slow down a vehicle through friction which is often installed close to the wheels. It stops or slows an action imminently.
"Pull the Brakes!"