This is the 3674th most frequent Polish word.
jaworznie
"Jaworznie" is not a standalone word in Polish; it may refer to "Jaworzno," a city in Poland.
Here 'Jaworznie' is used as a proper noun, the name of a city, in the locative case, functioning as a subject of the sentence.
Jaworznie to piękne miasto.
Jaworznie is a beautiful city.
In this sentence, 'Jaworznie' is again a proper noun in the locative case, used to indicate the place related to the preposition 'w' (in).
Byłem w Jaworznie w zeszłym tygodniu.
I was in Jaworznie last week.
Here 'Jaworznie' is used as a proper noun in the genitive case, indicating possession or association with the city.