When you need to urinate, you release the pressure on the urethra so that urine can flow. You do this by simply squeezing and releasing the pump. This action pulls the fluid out of the cuff and sends it to the balloon. Because the empty cuff is no longer pressing the urethra closed, the urine can flow out of the bladder.
Minutes after the bladder is empty, the fluid automatically returns from the balloon to the cuff. Once the cuff is refilled, the urethra is squeezed closed again.