It's one o'clock.
Es la una.
It's two o'clock.
Son las dos.
It's nine o'clock.
Son las nueve.
It's ten o'clock.
Son las diez.
It's three o'clock.
Son las tres.
It's 1:15.
Es la una y cuarto.
It's 1:30.
Es la una y media.
It's twelve o'clock.
Son las doce.
It's seven o'clock.
Son las siete.
It's six o'clock.
Son las seis.
It's 12:30.
Son las doce y media.
It's eight o'clock.
Son las ocho.
It's eleven o'clock.
Son las once.
It's five o'clock.
Son las cinco.
It's four o'clock.
Son las cuatro.