"The bee eats the orange."
Translation:L'abeille mange l'orange.
Only most of the time. The h is tricky in French, because some words which begin with h, especially words of Greek origin or other foreign loans, have the "h aspiré." That means that while the h isn't exactly spoken, it does block elision and liaison, thus: le héros (the hero). I'm sure that the Duolingo course addresses this eventually.
(Edit: Apparently most of the words with the "h aspiré" are of Germanic origin, onomatopoeia, or other foreign origin.)
Oh, that had nothing to do with the word "homme;" instead, it was because of the word "porc." Let's start with the orange first. See, in French, just as English, an orange is seen as a discrete, individual object. Thus someone can come by and eat one orange, that is, THE orange in the sentence. So, just the definite article is needed, if it is definite: l'orange. As for pork, or pig meat, however, French and English both see it as a mass noun, so one can't eat all the pork, ever; only all the pork which was served or at least SOME OF THE pork. In that situation, the "partitive article" or the contraction of "de" and the definite article is needed. Because "porc" is a masculine word, French uses the contracted form "du" to mean "of the, or some of the;" as in the phrase "du porc, some of the pork." So, the phrase "L'homme mange du porc" means "The man eats some (of the) pork," and the phrase "L'abeille mange l'orange" means "The bee eats the orange."