Yeld
It means traffic can pass on either side of an obstruction such as an island.
When a traffic light blinks red it means 'yield,' so proceed as if it were a four way stop sign. I've never heard of one blinking only yellow.
railroad
The sign is a yellow diamond with a black +. The sign MAY also contain text such as Crossroad ahead.
Traffic sign Road sign Warning sign Information Visual symbol
Tourist information
Yield. It usually means the cross-traffic has a blinking red light (stop sign). slow down because someone may pull out
Well, yes, it warns you that the lanes are going to merge soon into one road. If it wasn't there, drivers may not understand that they must adjust their speeds to safely merge, rather than assume other traffic must wait for them.
A oneway roadway with traffic coming agaisnt you
US standard traffic warning signs are yellow background with black symbols or letters. Traffic warning signs in other countries are generally white or yellow background with a red or black border in a triangular shape. Industrial warning signs are various colors, including OSHA and ANZI standards with orange background and black lettering. A yellow OSHA or ANZI sign would mean "caution" not "warning".
A yellow Star of David was the sign of a 'Jude' or Jew.