The passive voice is used when the subject receives an action. Japanese has a unique "adversative passive" that expresses annoyance or inconvenience.
Sensei ni homerareta.
I was praised by the teacher.
Ame ni furareta.
I was caught in the rain. (adversative passive)
Kono hon wa sekaijuu de yomarete iru.
This book is being read around the world.
Saifu wo nusumareta.
My wallet was stolen.
Nihongo wa Ajia de hanasarete iru.
Japanese is spoken in Asia.