Most of the world follows the Vienna Convention on Road Signs and Signals, where all the important road signs are understandable without reading. This is how no entry signs look around the world [1]

Especially important in places like Europe, where it's common for the driver to be able to read, but unable to speak the language of the country they are currently driving through. I can't speak any Polish, but can travel on Polish roads just fine

1: https://en.wikipedia.org/wiki/Prohibitory_traffic_sign#No_en...