Look for a square or an X (or a square with an X in it) right Infront of the stop line for the lights. If it’s there, that detects a car waiting.

There may be more of them further up the road to detect more cars waiting/arriving.

They are basically using big loops of wire to detect cars through magmatism.

They tend not to detect cyclists, so I often have to move to the side and wave cars forward so lights on side streets will change.