This light will come on briefly when you turn on the ignition, but the engine is not running, as a check to show you it is working. Then it should go out when the engine starts.
If the light stays on or comes on while you are driving, you may have a problem with the electrical charging system. It could indicate that you have an electrical problem. Have it checked right away. Driving while this light is on could drain your battery.
If you must drive a short distance with this light on, be certain to turn off all your accessories, such as the radio and air conditioner.