This is the 1609th most frequent Polish word.
lasach
"Lasach" means "forests" (locative or instrumental plural form of "las").
Here, 'lasach' is in the locative case, used after the preposition 'po' to indicate location.
Wędruję po pięknych lasach górskich.
I roam through beautiful mountain forests.
In this sentence, 'lasach' is in the locative case, indicating where the action of finding occurred after the preposition 'w'.
Znalazłem ciekawe grzyby w lasach.
I found interesting mushrooms in the forests.
Again, 'lasach' is in the locative case associated with the preposition 'w', emphasizing the location related to the action of taking care.