This is the 948th most frequent Polish word.
pokoju
The Polish word "pokoju" means "of the room" or "of peace," depending on context (genitive case).
In this sentence, 'pokoju' is the locative case of the noun 'pokój', which means 'room'. It indicates the location where the action is taking place.
Dzieci bawiły się w pokoju.
The children were playing in the room.
Here, 'pokoju' is in genitive case form of 'pokój', meaning 'peace', used to express the need for or lack of something.
Potrzebujemy więcej pokoju na świecie.
We need more peace in the world.
In this case, 'pokoju' is the genitive case of 'pokój', meaning 'peace', used to indicate possession or association.