Let’s answer to the question, “Ima Nan-ji desu ka”.
“Ichi-ji desu.” means “It is 1 o`clock.”
Ni-ji means 2 o`clock.
San-ji: 3 o`clock
Yo-ji: 4 o`clock
Go-ji: 5 o`clock
Roku-ji: 6 o`clock
Nana-ji: 7 o`clock
Hachi-ji: 8 o`clock
Ku-ji: 9 o`clock
Jyuu-ji: 10 o`clock
Jyuu-ichi-ji: 11 o`clock
Jyuu-ni-ji: 12 o`clock