This is the 4997th most frequent Russian word.
лесником
The Russian word "лесником" means "forester" in English.
The word 'лесником' is used as an instrumental case indicating the role or occupation of 'forester' that the subject took.
Лесником был мой дед, много лет проработавший на благо природы.
My grandfather was a forester, having worked many years for the benefit of nature.
Here, 'лесником' is instrumental case, referring to the capacity in which the subject worked.
Он гордился своим трудом лесником, охраняя лес от браконьеров.
He was proud of his work as a forester, protecting the forest from poachers.
Again, 'лесником' is in instrumental case to describe the profession or role he aspired to.