This is the 37th most frequent Swedish word.
sina
"Sina" is a possessive pronoun in Swedish meaning "their" (referring to plural possessions).
Posessive pronoun 'sina' refers to the same subject as the doer 'Katten'.
Katten tvättar sina tassar.
The cat washes its paws.
Posessive pronoun 'sina' indicates that each of the children plays with their own toys.
Barnen leker med sina leksaker.
The children play with their toys.
Posessive pronoun 'sina' refers to the object (friends) belonging to the subject 'Hon'.