When people eat desayuno is when they wake up at home.People have desayuno at 9:00.
When you are wating for lunch you have aperitivo. People have aperitivo at 12:00.
In Spain usually you have a hot meal. People eat lunch at 1:00 or 2:00.
Merienda is a snack that people eat about 5:00.Because dinner is late.
Usually is a small meal.People eat it dinner at 8:00 or 10:00.