This is the 7664th most frequent Polish word.
litwina
"Litwina" in Polish means "a Lithuanian woman."
In this sentence, 'Litwina' is in the accusative case, indicating the direct object of the action.
Litwina spotkałem w parku.
I met the Lithuanian in the park.
Here, 'Litwina' remains in the accusative case as the direct object of knowing.
Znam Litwina od lat.
I have known the Lithuanian for years.
Again, 'Litwina' is in the accusative case as the direct object of the verb 'widzieć' (to see).