This is the 1707th most frequent Polish word.
rodzinie
"Rodzinie" means "to the family" or "for the family" in English.
This usage indicates the dative case of the noun to indicate the object of the preposition 'o'.
Mówiłem o mojej rodzinie w szkole.
I talked about my family at school.
The prepositional case indicates location or association with 'w'.
Chciałbym pomóc w rodzinie mojej siostry.
I would like to help in my sister's family.
Here, the dative case emphasizes the topic of conversation involving the preposition 'o'.