You are merging with a roadway from the left. Give right-of-way and don’t turn left

What is the meaning of the following traffic signs?

1. Correct answer: You are merging with a roadway from the left. Give right-of-way and don’t turn left.
2. T-Intersection. It is allowed to turn to the side road.
3. Dead-end road ahead. Entry to this road is forbidden.
4. It is always required to make a complete stop and give right-of-way to merging traffic from the right.