What is the meaning of the following traffic sign?

1. Correct answer: Driving in the direction marked with a yellow arrow is permitted for public transportation only.
2. You have right of way on the narrow road.
3. Give right-of-way to opposite motor traffic on a narrow and steep road.
4. Drive only forward. Turning is prohibited.

WhyA yellow arrow pointing toward you means only public transport may drive in that direction. Everyone else follows the white arrow.