Meaning of SIGNAL in English

(EQUIPMENT) [noun] [C] - equipment, esp. on the side of a railway or road, often with lights, which tells drivers whether they can go, must stop, or should move more slowlya railway signala traffic signala road signalA signal box (US signal tower) is a building from which railway signals can be operated.

Cambridge English vocab.      Кембриджский английский словарь.