You already know a small electrical motor. When you switch the motor on it starts running. This happens with many different home appliances such as an electrical whisk, an electrical train or a fan.

However, a motor can also be used as a generator.
Fasten the motor and put the pulley on the shaft.
Connect the two poles to a light bulb and see what happens when you turn the shaft.
Use a piece of string to make it easier to turn the wheel.