DC motor module starts to turn the motor when it receives a signal from the input. The motor spins faster as the value of the signal increases. The switch on the board lets that you choose which direction the motor spins. If it is in the “forward” mode, the motor spins clockwise and your car goes forward. In the “backward” mode, the motor spins counter clockwise and your car goes back. Also, there is the third mode. It is called the “smart” (middle) mode. When you use it, your car stops at 2.5V, it gets faster to forward from 2.5V to 5V and to backwards from 2.5V to 0V. You can use the module for right wheels because of its shaft direction.