Two flashes of headlight means “GO”! This is a common signal to tell the other driver that he can go ahead!
This courtesy idea or culture originally was observed in Philadelphia area that a group of drivers tried to give way to each other at the STOP sign when both cars approached the spot at same time!
( It was also heard that during the independence war, a group of soldiers in Philadelphia gave two quick flashes of light to tell the other group of soldiers to take an attack action ! Since then it became a tradition!)
First flash means G and second flash means O, combining two quick flashes then it means “GO”!
It has to be two quick flashes, if you do three quick flashes then it could mean something else! 😆