This is the 7334th most frequent Polish word.
karoliny
"Karoliny" is the plural form of "Karolina," which is a Polish female given name (equivalent to "Caroline" in English). It can also refer to places or items named after Karolina.
Here, 'Karoliny' is used in the genitive case to express possession, showing that the house belongs to someone specific, namely, Karolina.
Ten dom należy do Karoliny.
This house belongs to Karolina.
In this sentence, 'Karoliny' would not be correct; 'Karoliną' is used in the instrumental case after 'z' (with).
Idziemy na spotkanie z Karoliną.
We are going to a meeting with Karolina.
'Karoliny' is again in the genitive case, here used to denote possession of the book by Karolina.