This is the 344th most frequent Czech word.
domu
"Domu" means "home" or "to home" (indicating movement toward home).
Here, 'domu' indicates the direction 'to home' or 'towards home', functioning as an adverb.
Jdu domu.
I am going home.
Here, 'doma' is used to denote the location 'at home', functioning as an adverb to specify the place.
Dnes večer budu doma.
Tonight, I will be at home.
Here, 'domu' is used in the genitive case of 'dům', indicating possession or relation, specifying 'of the house'.