This light should come on briefly when the ignition is turned on as a check to let you know that the light is working.
If this light comes on and stays on while the engine is running, it means your engine is low on oil. You need to check the oil level as soon as possible. See Engine Oil for further information.
Notice: Lack of proper engine oil maintenance can damage the engine. The repairs would not be covered by the vehicle warranty. Always follow the maintenance schedule in this manual for changing engine oil.