It can be the turn signal switch.
Two possibilities. one: there is a switch that when depressed turns on the light, it could be stuck. I haven't looked for one on this car. two: your brake is not fully releasing as cable has gotten rusty. Look under car and see if you can give it a yank and it releases.
It is self-adjusting, normally.
On the brake pedal.
On the brake pedal assembly.
A lubricant on your 1995 Ford Mercury emergency brake can help to get it unstuck. Tapping on the emergency brake with a rubber mallet might also help.
Just normal DOT3 brake fluid.
The emergency brake cable is probably seized and the emergency brake is not releasing.
'P'arking or emergency brake
This is usually cause by a stuck brake light switch on the brake pedal. Replace it.
In a repair manual or online.
Mounted to the firewall on the driver's side.
If the brake lights stay on that probably means the switch on the brake pedal that activates them is defective.
first check your brake fluid it may be low then check the switch at the emergency brake lever it may be stuck