This is the 2606th most frequent Polish word.
twierdzi
"Twierdzi" means "claims" or "asserts" in English.
In this sentence, 'twierdzi' functions as a verb meaning 'claims' or 'asserts', used to relate someone's statement.
On twierdzi, że wszystko jest w porządku.
He claims that everything is fine.
Here, 'twierdzi' depicts the teacher's estimation or assertion of the situation.
Nauczycielka twierdzi, że uczniowie dobrze zrozumieli materiał.
The teacher states that the students understood the material well.
In this context, 'twierdzi' conveys a strong expression of personal conviction.