This is the 12262nd most frequent Polish word.
mieszkały
"Mieszkały" translates to "they lived" in English.
Here, 'mieszkały' is the third-person plural past tense of the verb 'mieszkać' (to live), used for a group of females.
Mieszkały tam przez wiele lat.
They lived there for many years.
In this sentence, 'mieszkały' refers to a group of female witches residing habitually in the castle in the past.
W dawnych czasach mieszkały w tym zamku czarownice.
In ancient times, witches lived in this castle.
This sentence demonstrates 'mieszkały' used to describe the habitual action of a group of females living in the countryside in the past.