The timing belt is part of an engine that controls the timing of the opening and closing of the engine’s valves. In a typical engine, the timing belt the engine’s crankshaft to the camshafts, which in turn control the valves.
If something goes wrong with the timing of the opening and closing of the valves, then the engine will at least run poorly, or will not run at all. In fact, then engine could be destroyed if the valves collide with the engine’s pistons (this can and does happen in some engines when the timing belt breaks).
Timing belts should be replaced long before they wear out. If a timing belt wears out or breaks then the damage will be immediate and severe. A&B Transmission and Auto can inspect and replace your timing belt during scheduled maintenance, or as part of any other routine maintenance you may request.