This is the 10100th most frequent Polish word.
biegnący
"Running."
Here, 'biegnący' is used as an adjective to describe the man who is running.
Biegnący mężczyzna zerknął na zegarek.
The running man glanced at the watch.
In this sentence, 'biegnący' is an adjective describing the path which runs through the village.
Znaleziono list biegnący przez całą wieś.
A path running through the entire village was found.
Here, 'biegnący' is used as a present participle to describe the boy who is in the action of running.