This is the 3078th most frequent Polish word.
posterunku
"Posterunku" means "post" or "station," typically referring to a police station or outpost.
Here, 'posterunku' is used as a noun in the locative case, referring to a physical location, specifically a police station.
Idź na posterunek policji, aby zgłosić zgubienie dokumentów.
Go to the police station to report lost documents.
In this sentence, 'posterunku' is used as a genitive singular noun, denoting possession or responsibility of the commander belonging to the station.
Dowódca posterunku rozkazał przygotować raport.
The commander of the station ordered to prepare a report.
The word 'posterunku' is used in the locative case here as well, describing the context of the location where the work occurs.