Not an expert but I think they are just ‘proving’ lights as in they prove the points are set correctly. Also, they (or some of them) are primarily for shunt moves so you would run a loco behind the points and ground position light, switch ends and await for the ground position light to clear. But as a train coming from a main aspect, you would
still require them to be clear otherwise you must stop and report it to the signaller. If you came from a main aspect, you would get no indication in the theatre box of any ‘proving lights’ but you would (on some of them) get an indication if doing a shunt and that is the starting signal to take you back in to a station or loop.
They tend to be found at complex junctions/stations or on entrance to goods loops. In other words, where shunt moves can be done.