This is the 13516th most frequent Polish word.
pełnić
To fulfill, perform, or carry out.
Here, 'pełnić' is used to describe someone performing a role or function.
On pełni rolę lidera w zespole.
He fulfills the role of a leader in the team.
In this sentence, 'pełnić' refers to carrying out responsibilities or tasks associated with a position.
Pełnię obowiązki nauczyciela w tej szkole.
I am fulfilling the duties of a teacher at this school.
Here, 'pełnić' signifies undertaking specified duties or a role during a set time.