hello, my brake light just came on, on my 69 280 se is it for brake fluid or e brake?

Hi,
That would be the brakes rather than the fluid. I cannot recollect the exact year when that series started running with brake pad sensors, but it could also be the brake sensor wiring that is corroded or shorting.

Brake Lights are very important part of your vehicle because when you take brake the brake light glows and thus it helps the other vehicle on the road to find that you are taking brake..so it is needed to be repaired...or change the entire kit..