This is the 318th most frequent Ukrainian word.
будинок
House.
Here, 'будинок' is used in the nominative case to refer to a 'house' as a dwelling.
Я живу у великому будинку.
I live in a big house.
Here, 'будинок' is in the accusative case, and it denotes a specific house being constructed.
Мій друг будує новий будинок неподалік.
My friend is building a new house nearby.
In this sentence, 'будинок' is in the accusative case as the direct object of the sentence, referring to a particular house observed.