Doing things at a certain time
It is different saying it's two o'clock than saying I have breakfast at two o'clock.
In Spanish, we say it this way:
¿A qué hora desayunas?
Desayuno a las siete de la mañana.
¿A qué hora comes?
Como a la una de la tarde.
When we want to say I go to the gym on Monday mornings, we'll say voy al gimnasio los lunes por/en la mañana. As soon as we include the specific time, we have to switch to de: voy al gimnasio los lunes a las 9 de la mañana.
Progress, Vol. 1
Progress, all volumes
