Ok,so i don't know what the hell it is.It was lit up on my piranha today for a few minutes.I noticed my SE has the same goofy idiot light(not lit though).I must be a real BIG idiot,because I don't know what the friggin thing means...[dunno]
(from http://www.myfordfocus.com/underthehood.htm)
Engine Cooling System
If your Focus has the 2.0L Zetec engine, your have what is referred to as "fail-safe cooling". This is a handy system, should for some reason your engine's coolant supply become depleted, the fail-safe cooling allows the vehicle to be driven temporarily before any incremental component damage occurs. The fail-safe traveling distance depends on ambient temperatures, vehicle load, and terrain.
If your engine begins to overheat, the coolant temperature gauge will move into the red area, and the multi-function automatic transaxle/cooling system light on your instrument panel will be illuminated. When the engine reaches a preset over-temperature condition, the fail-safe cooling system will activate. The engine will switch to alternating cylinder operation, each disabled cylinder acts as an air pump, thereby cooling the engine.
When this happens, your vehicle will still operate, however... the engine power will be limited, since you are not running on all four cylinders, the air conditioning system will be disabled, and your check engine light on the instrument panel will illuminate. Continued operation will increase the engine temperature and eventually the engine will shut off, and you will loose your power steering and bracking. If at all possible, you should pull off the road and let the engine cool. If you car does shut off, and once your engine cools down, you should be able to start the car again. You should however get your car to a service facility as soon as possible.