This is the 280th most frequent Croatian word.
kući
"Kući" means "home" (to the home).
Here, 'kući' is used as an adverb to indicate the direction 'to home'.
Idemo kući nakon škole.
We are going home after school.
In this sentence, 'kući' serves as an adverb describing the state 'at home'.
On je kući cijelo popodne.
He is at home the entire afternoon.
In this case, 'kući' is an adverb that specifies a destination, 'to home'.