What is the meaning of the following traffic sign?

1. Crossroad ahead.
2. Merging of a roadway having right-of-way with a side road to its right (turning to the side road is allowed).
3. Correct answer: You are approaching a side road merging from the right (turning right is prohibited). You have right-of-way over traffic coming from the side road.
4. Give right-of-way to traffic coming from the road that merges from the right.

WhyOn the sign your road is the main one, and a minor road merges into it from the right. You may not turn onto it here, and drivers coming from it must let you pass.