This is the 3483rd most frequent Polish word.
znać
"Znać" means "to know" (to be familiar with someone or something).
The word 'znam' (from 'znać') is used here to express knowledge or acquaintance with a person.
Znam tego człowieka bardzo dobrze.
I know this person very well.
The word 'znam' (from 'znać') is used in this context to signify being unaware of certain information or facts.
Nie znam odpowiedzi na to pytanie.
I don’t know the answer to this question.
The word 'znać' in this context is used to indicate proficiency or familiarity with languages.