The main thing to memorize here is that number of an hour will be with a feminine article (la, las), because it means “it is one hour”, where “hour” is hidden, e.g. Es la una (hora). Hora – feminine noun.

Es la una – it is 1 o’clock

Es la una y cinco – it is 1:05

After 1, numbers become plural:

Son las dos – it is 2 o’clock

Son las tres – it is 3 o’clock


Son las dos y media – it is 2:30

Y media – half past … , i.e. 30 minutes

Son lass diez y cuarto – It is 10:15

Y cuarto – and 15

Son lass tres menos diez – it is 2:50/it is 3 without 10, that literally means “it is 3:00 minus 00:10”.

Son las cuatro menos cuatro – it is 3:56 (it is 4 without 4)

Salimos a las ocho – we leave at 8

Vendremos a las cinco  – we will come at 5