Stop

you go again whenever there are no other cars in the way

Is it like a "warning" sign?

kind of they're usually at small intersections without traffic lights to prevent cars from crashing

Ah, in the UK we have something called "Give Way" which is a triangle pointing down, that's at things like crossroads and T junctions and it basically means "If there's another car passing the other way (IE across the T junction when you are coming up into it) then give it right of way and let it go before you."