Easiest way to explain it would be that it's like ABS but when accelerating.
With traction control you can floor it on wet grass and the vehicle will sense the tyres spinning it applies the brakes to that wheel to stop it from spinning.
lots of vehicle have traction control for general driving but a few 4x4s/SUVs have traction control systems designed for off road use, they doesn't so much try to stop the wheels from spinning but tries to send power to the wheels with the most traction, it relies on sensing that a or multiple wheels have lost traction so will apply the brakes to those wheels to allow the other ones to drive (assuming no axle diff lock).
In low traction situations it's smart enough to not just lock up all the wheels and stop you from moving but depending on what mode you are in (if it has modes) then it will react different for sand or snow or tarseal.
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