es la una

it's one o'clock

→ ser
phrase Rare #30,198
it's one o'clock Used to tell the time when it is one o'clock. The feminine form la una is used because hora is understood. For times around one, Spanish uses expressions such as es la una menos cuarto and es la una y cuarenta y cinco.
SP: Es la una de la mañana y todavía no tengo sueño.
EN: It's one in the morning and I'm still not sleepy.

Ya es la una de la mañana y todavía yo no me duermo.

It's already one in the morning and I still can't fall asleep.

Es la una y cuarenta y cinco.

It’s quarter to two.

Es la una de la tarde.

It's one o'clock in the afternoon.

Es la una.

It’s one o’clock.

Es la una menos veinticinco.

It’s twenty-five to one.

Ya es la una.

It's already one o'clock.

— Amarcord (1973)

Es la una de la mañana.

It's one in the morning.

Es la una menos cuarto.

It's quarter to one.