This is the 16553rd most frequent Polish word.
więzieniach
"Więzieniach" means "prisons" (in the locative or instrumental plural form) in English.
The word 'więzieniach' is used as the locative plural form of 'więzienie', meaning that prisoners are physically located within prisons.
Więźniowie znajdują się w więzieniach.
Prisoners are located in prisons.
Here, 'więzieniach' indicates the location being discussed in regard to conditions, emphasizing the state of these places.
Warunki w więzieniach powinny być humanitarne.
Conditions in prisons should be humane.
In this sentence, 'więzieniach' conveys the setting where rehabilitation programs take place, focusing on the activities within the prisons.