This is the 4553rd most frequent Polish word.
leśne
"Leśne" means "forest-related" or "woodland."
The adjective 'leśne' describes the type of berries ('jagody'), specifying that they are from the forest.
Dzieci zbierały jagody leśne.
The children collected forest berries.
Here, 'leśne' is used to describe the birds ('ptaki'), indicating that they live in or are characteristic of the forest.
Te ptaki leśne mają piękne głosy.
These forest birds have beautiful voices.
In this sentence, 'leśne' modifies the plural noun 'ścieżki' ('paths'), describing their location in the forest.