first of all, what color is it, if its a green light bulb (under gas, and temp gauge on right side) with it looking like its on then that means the head lights are on,
if its the read one (looks like the rear lights are on) underneath the speedometer, then that means a light bulb is burnt,
so walk around the car and check all the lights,
then to check the brake lights, ask a friend to step on the brakes to check and see if in fact it is the brake light, if there is no one able to help you, place a heavy item on the pedal so that you could check it out.
if you want to check the DRL (day time running lights) release the e-brake if it is applied, and it will turn on the DRL's (car has to be on first)
that should do the trick B)