This is the 6394th most frequent Russian word.
часу
The Russian word "часу" is the genitive or dative singular form of "час," meaning "hour."
The word 'часу' is used here in the dative case, implying a point in time (hour) to which an action is oriented.
Подождите до следующего часу.
Wait until the next hour.
In this sentence, 'к часу' employs the dative case, indicating an approximate time by which an action (being home) will occur.
К часу мы уже будем дома.
By one o'clock, we will already be home.
The use of 'часу' here is in the dative case combined with 'вокруг,' denoting a time period around the specific hour.