I am going to guess it is because depending where you live in America the third major meal of the day is called dinner instead of supper.
Where I grew up in Minnesota, we called the three major meals breakfast, dinner, and supper. Where I live now in another part of the state we call them breakfast, lunch, and dinner. And to make it more confusing in my house we often call them breakfast, lunch, and supper. How does my brain not explode over this?
- (li kaj ŝi) manĝas = (he and she) eat
- matenmanĝas = eat breakfast
- tagmanĝas = eat lunch
So your sentence would mean “He and she eat eat breakfast and lunch.” Eo words ending in -as are verbs in the present (mi manĝas = I eat, vi manĝas = you eat etc.).
In case you were looking for the words “breakfast” and “lunch” (without “eat”), they are “matenmanĝo” and “tagmanĝo.”
This discussion page seems to be about the eo → en translation but Dylan's question is about the Esperanto sentence. So it's not so easy to answer.
Certainly the Esperanto sentence could be reformulated using “ili” or “la viro kaj la virino.” All those yield meaningful and perfectly acceptable sentences in Esperanto. The respective English translations could then be (barring discussions about lunch / dinner / supper and the like):
- They eat breakfast and lunch.
- The man and the woman eat breakfast and lunch.
So much seems rather elementary. I can see why we would discuss about different translations into English but why would we discuss about different originals in Esperanto?
One could equally well ask “why isn't it 'bonan matenon'.” The course contributors choose the sentences. Somebody might ask “is xyz also a valid sentence” but not “why couldn't it be xyz.”
Something keeps telling me I am missing something… FredCapp obviously got what it's all about.
"He and she eat breakfasts and lunches" should be accepted. It is not specified whether the sentence is describing an event (they go out and eat two meals together) or a habit (both of them regularly have breakfasts and lunches - unlike me who sleep until it's time for lunch).