What is the Nissan Sentra indicator light on the penger side of dashboard?

I just bought a 2000 Sentra with no owner's manual. There is a little light mounted where the windshield meets the dash on the penger side, and it blinks every few seconds when the car is off. What is it the indicator for? Penger airbag, perhaps? If so, does blinking mean that it's functioning, or that it is NOT functioning?