Those signs differ from country to country, but the design is very similar. In Germany this sign looks like this

https://de.wikipedia.org/wiki/Verkehrsberuhigter_Bereich#/me...

The official meaning is "begining of a traffic calming area" (verkehrsberuhigter Bereich) but most people call it "Spielstraße" (literal translation "street for playing"). I don't know if the sign was designed after the common term for those streets or vice versa.