What is the meaning of Traffic_light?

A signalling device positioned at a road intersection or pedestrian crossing indicating the moment it is safe to drive, ride or walk, using a universal color code.

A road intersection controlled by one or more such devices.

A colour code using the three signals of a traffic light (green, yellow or amber, and red) as a metaphor.

The colored dots on stamp sheet margins printed with offset printing or photogravure methods, used by the printers to check color accuracy.

Source: wiktionary.org