This is the 3941st most frequent Polish word.
swoją
"One's own."
In this sentence, 'swoją' serves as a possessive pronoun reflecting ownership relative to the subject 'Ona' (She), and is in the accusative case to agree with the noun 'rodzinę' (family).
Ona zawsze dba o swoją rodzinę.
She always takes care of her family.
Here, 'swoją' acts again as a possessive pronoun indicating that the sister belongs to the subject 'On' (He), and adopts the instrumental case to agree with 'siostrą' (sister).
On poszedł do sklepu ze swoją siostrą.
He went to the store with his sister.
In this example, 'swoją' denotes possession of the toy relative to the subject 'Dziecko' (The child), and is in the accusative case aligning with the noun 'zabawkę' (toy).