There are oen ON/OFF switch and one potentiometer on the controller. The OF/OFF is a reversal switch. The pot has five wires, two as the power switch, three as the pot. Turn the pot to the mini end, the controller will be powered off.
The power switch is on, the controller is powered on. The power switch off, the motor will be brake.
The reversal switch on, the motor forward, the switch off, the motor backward. When the motor change the direction of thr rotation, the motor will be braked and soft start to the setted speed.
When you turn the pot, the motor change the speed.