This is the 536th most frequent Ukrainian word.
її
"Її" means "her" or "hers" in English.
Indicates possession of the key by another entity (not the subject 'она').
Вона втратила її ключ.
She lost her key.
Indicates a specific object ('favorite flowers') related to the subject.
Її улюблені квіти — троянди.
Her favorite flowers are roses.
Refers to the noun 'work' as the object belonging to or associated with her.