How does the electric car work?

If you are talking hybrid, a small gas engine drives a generator that charges the batteries that drive the electric motors for the wheels. For small trips, just the battery is used and can be recharged at home. For extended trips, the gas engine runs to keep the batteries charges. As the gas engine runs at a constant rate, the emissions and fuel usage can be greatly reduced compared to a conventional car/engine.

If you are talking a battery electric car, the function remains the same except there is no gas engine to keep the batteries charged when it is not plugged in.

Locomotives on a train operate in a similar way as a hybrid. A big diesel engine turns a generator that supplies electrical power to the drive motors connected to the traction wheels on the rails. The engineer controls the electric power to the drive wheels instead of the diesel engine directly.