Spanish has specific verbs that correspond to each of the daily meals: desayunar, comer and cenar. Here’s what you need to keep in mind.
Avoid language such as *¿Quieres comer desayuno? Instead, simply say ¿Quieres desayunar? Do you want to have breakfast?
The verb comer is usually reserved for ‘lunch’, la comida, the large mid-day meal often eaten around 2 or 3pm. ¿Ya comiste? Have you had lunch?
For the evening meal, la cena, use cenar. Vamos a cenar tarde. We’re going to eat (have dinner) late. Dinner is a light meal, usually eaten around 8pm or 9pm.
You may have learned in school that almuerzo is lunch — and perhaps the word is used that way in some places. However, as we said above, the mid-day meal in Mexico is called la comida. Some speakers use almuerzo for a late breakfast or early lunch, brunch. The associated verb is almorzar (ue).
Direct objects with verbs of eating
Note that these can be verbs transitively: Recuerda que hoy vamos a desayunar unos chilaquiles muy ricos. Remember that today we’re having (some delicious) chilaquiles for breakfast. Cenar tacos al pastor. Have pastor-style tacos for dinner. As you can see from the glosses here, the usual way to express this idea in English is with have + direct object for + meal, so mental notes are called for.
There isn’t really a good translation for snack. Outside of a meal, comer can take on a generic meaning. ¿Quieres comer algo? Would you like something to eat?
By the way, when having lab tests done you may be asked to show up en ayunas, in a fasting state. If you look closely, you can see the resemblance to desayuno, which makes sense if you think of breakfast as the meal the breaks the fast.
Donde comen dos
A saying: Donde comen dos, comen tres. Where’s the food enough for two, there’s food enough for three. You can rework this for other occasions by swapping out the verb: Donde duermen dos …