This is the 7363rd most frequent Polish word.
kazimierz
"Kazimierz" is a proper noun, commonly a Polish given name equivalent to "Casimir" in English. It is also the name of a historic district in Kraków, Poland.
Here, 'Kazimierz' is used as a proper noun referring to a person's name.
Kazimierz to piękne imię.
Kazimierz is a beautiful name.
In this sentence, 'Kazimierz' refers to a historic district in Krakow.
Odwiedziłem Kazimierz w Krakowie.
I visited Kazimierz in Krakow.
Here, 'Kazimierz' again is used as a proper noun, designating a specific person, likely someone famous in history.