This is the 7349th most frequent Polish word.
katarina
"Katarina" is not a Polish word; it is a name used in various languages.
Here, 'Katarina' is used as a proper noun, being the name of a person who is the subject of the sentence.
Katarina poszła dziś do sklepu, aby kupić owoce.
Katarina went to the store today to buy fruits.
In this sentence, 'Katarina' still functions as a proper noun representing someone's name, and this individual was observed at an event.
Widziałem Katarinę podczas koncertu w piątek.
I saw Katarina during the concert on Friday.
The word 'Katarina' refers to a person being described in this statement, showing her qualities.