This is the 9796th most frequent Polish word.
znasz
"Znasz" means "you know" (second person singular).
The word 'znasz' is used here in the second person singular of the verb 'znać', meaning 'you know', in the context of being acquainted with someone.
Czy znasz tego autora?
Do you know this author?
In this sentence, 'znasz' retains its second person singular form, referring to familiarity with a place.
Jak dobrze znasz to miasto?
How well do you know this city?
Here, 'znasz się' is a reflexive form, meaning 'are you knowledgeable' or 'are you skilled' in a particular area, demonstrating expertise.