Why is my brake light on?

On the dash or back of car? If on the dash try releasing the parking brake a couple of times. Make sure it is fully released. If back of car pull up on your brake pedal. If that don't help unhook brake pedal switch. If light then goes out replace the switch.

Its the dash light. Thank u. I will try that. If it stays on still...then what? Is it ok to be driving it?

Also check you brake fluid level. If is low refill it and inspect car for where its leaking from. If fluid level is ok and there are no leaks then Try disconnecting the e brake switch. If light goes out replace the switch. If you have tried all of the above and light remains on I would take it to a certified brake mechanic to have inspected. Your safety and the safety of others relies on your brakes operating properly.