What is the meaning of this traffic sign?

- It is a warning, instruction or prohibitory sign, for public transport only.
- It is a square information sign.
- Correct answer: It is a warning, instruction or prohibitory sign, which conveys a message that is not covered by the provisions of the road sign table.
- It is an unofficial road sign, which conveys various optional guidances.
Why this is the answer
The correct answer in the official bank: It is a warning, instruction or prohibitory sign, which conveys a message that is not covered by the provisions of the road sign table.
A yellow sign with black writing is used for a warning, instruction or prohibition that has no dedicated symbol in the road sign table. It is binding and must be obeyed like any other sign. It is not an optional information board, and it is not meant only for public transport but for every road user its message covers.