This is the 799th most frequent Polish word.
lesie
"Lesie" is the locative case of "las," meaning "forest" in English.
Here, 'lesie' is in the locative case, used after the preposition 'w' to describe the place where the activity took place, the forest in this case.
Spacerowaliśmy w lesie i znaleźliśmy piękne grzyby.
We were walking in the forest and found beautiful mushrooms.
Here, 'lesie' is again in the locative case, following the preposition 'w', to denote the location of the activities and observations.
W lesie spędziliśmy cały dzień, podziwiając przyrodę.
We spent the whole day in the forest, admiring nature.
In this sentence, the word 'lesie' appears in the locative case again, indicating the place where the deer lives, referenced with 'w'.