Do you have the right of way over all vehicles at an intersection marked in such a way?

Why?

The A-5 crossroads sign warns of a junction where the roads have equal priority; it does not give you priority. You must give way to vehicles approaching from your right. When turning left, you must also give way to oncoming vehicles going straight ahead or turning right.

Art. 25 ust. 1 Prawa o ruchu drogowym; § 5 ust. 1 rozporządzenia w sprawie znaków i sygnałów drogowych