I think it stands for traffic management control or similar.
On mine it shows little road signs on the on screen map indicating delays and crashes etc. Reduced traffic flows are indicated with little chevrons (>>>) with the number indicating the severity of the delay and direction of affected traffic flow.
When the satnav is in use and you have a route programmed in, alternative routes are offered if you encounter a delay/road closure and the system announces of impending trouble. "...accident 17 miles ahead".
I'll post some pics when I can.