Time is giving in Spanish with the verb ser + article definite + basic figure (without " hora"):

¿Qué hora es? Es la una. Son las seis en punto. What time is it? It is one o´clock It is six o´clock.

In the everyday life one uses mostly only the numbers of 1-12 and specifies if necessary the time of day:

Las 10 de la mañana. 10 in the morning.

Minutes, quarter and half hours add the conjunction "y" before the full hour and after the half it will add "menos":

Las cuatro y cinco. Five after four.

Las siete y cuarto. Quarter past seven.

Son las tres menos cuarto. It´s quarter to ten.

Son las tres menos diez. It´s ten to three.

To specify at which time something happens ('around), one uses the preposition "a":

¿A qué hora nos encontramos/vemos/quedamos? At what time can we meet each other?

A las tres, ¿de acuerdo?At three, O.K.?

The numbers from 13 to 24 are used above all with official times and with "horas" and "minutos":

13:15 Las trece horas (y) quince minutos. 13:15 Thirten hours fifteen minutes.