The metal "box" is known as motor, but in the experiment is used as a generator. Inside the motor is a coil, which rotates inside a magnetic field. When the "fan" is moving the kinetic energy derived from our hand, is converted initially to kinetic energy on the coil and then into electrical energy. 
With similar way operate all electro generators
You need:
2 cables with crocodile clips at the end
1 microammeter
1 small motor
fun (you can create it from cardboard)
