Push down on the parking brake handle. If the light stays out, the cable is stretched and needs to be adjusted or more commonly on Fords, a rear cable is sticking and is not fully released. The same light will turn on if the brake fluid is low. Don't add any fluid. That means you either have a leak that must be addressed right away, or more likely it is just time for a brake inspection, and most likely you'll need new front brake pads. The fluid level will go back up once the new pads are installed.
That light also warns of an imbalance in the two hydraulic systems, typically from a leak. That is not likely here since the light is only flickering.