This is the 7508th most frequent Polish word.
kristiana
The word "kristiana" does not appear to be a standard Polish word. It may be a proper name or a misspelling.
Here, 'Kristiana' is used as a proper noun, referring to a person's name.
Kristiana jest moją przyjaciółką.
Kristiana is my friend.
Here, 'Kristianę' (accusative case) is used in the context of asking if someone has met this person.
Czy spotkałeś kiedyś Kristianę?
Have you ever met Kristiana?
In this context, 'Kristiany' (genitive case) is used to talk about something belonging to Kristiana.