Traction Control.....

I don't know exactly about the TCS in this exact system, but theres a general theory behind it. Basically, a TCS system is usually integrated onto a car with ABS (they could work indepent of each other), and it's used to control wheel slip acceleration; ABS would control wheel slip deceleration in a panic situtation. An example would be that you're on a gravel road, and you accelerate to quickly, and you lose traction. TCS, monitoring the wheel speed using sensors, which relays information to the ECU which decides what action it needs to take to control the wheel from spinning and possibily sending you out of control. The system could do this by many ways (Which I am uncertain for Fords specific system, but I would guess its close); Retarding the timing, which would instantly drop engine RPMS, it could possibly take even more action by limiting fuel, closing throttle, and even in some cases it could apply the brake, which would help you gain traction.

If TCS is on, whats slipping would be your wheel under acceleration due to lack of traction, and it doesnt hurt anything when TCS is in effect, its there for your benefit, but you can turn it off.