This is the 7457th most frequent Polish word.
kopalnia
Mine (a place where minerals are extracted).
In this sentence, 'kopalnia' is used to refer to a physical location where minerals, specifically coal, are extracted.
Kopalnia węgla znajduje się na obrzeżach miasta.
The coal mine is located at the outskirts of the city.
Here, 'kopalnia' is used metaphorically to signify a source of abundant and valuable information.
Ta książka to prawdziwa kopalnia wiedzy.
This book is a real treasure trove of knowledge.
In this sentence, 'kopalnia' is associated with its traditional meaning as a workplace for miners extracting resources underground.