So, just to clarify: You can say "Ella lee un menu" and mean "She read a menu", but if there is an indirect object (you all, in this case), you can say both "Ella les lee un menu a ustedes" and "Ella les lee un menu", but the later is non-specific and could mean "She read them a menu" as well as "She reads you all a menu". Did I get that right?
Undead goat did a noble job explaining the redundancy in Spanish of using an indirect and direct object in the same sentence. In the sentence, the LES is not optional. It is a hard concept for English speakers to grasp. There is no parallel. When you see that personal A, you have to be ready for a direct object, too. Hope this helps someone. I can understand this completely through text, but I'll be darn if I could incorporate it in conversation.
So basically 'les' has more than one meaning. It can mean 'them' or 'you' (plural). Then, you need to clarify the meaning of 'les'. For les to mean 'them', you add either, 'a ellos' (to males/ males and females) or 'a ellas' (to females). For les to mean you (plural), you add 'a ustedes'. (I think...)
I have heard that the abbreviation of 'usted' is Uds. (Please correct me if I'm wrong), and I thought of this strange, hypothetical question: Say you wrote a formal letter asking the Queen of England, ""¿Cómo está usted?" Could you abbreviate the 'usted' in "¿Cómo está usted?" to Uds? Would that be considered impolite?
I think the computer is programmed to accept "you" as well as "you all," which one seldom hears in English, and even "y'all," which as a southerner I've successfully used with Duo. But I'd be reluctant to try "you-uns," or "yunz," as you sometimes hear in the Allegheny mining country.
In Spanish, when a verb has an indirect object, this MUST be indicated by a clitic pronoun on the verb: "Les lee un libro" could mean "she reads them a book" or "she reads you [plural] a book" all on its own. In English, we think of a pronoun as standing in the place of a noun, for example "to them" might "stand for" "to the children." There are other circumstances in Spanish where pronouns behave differently than in English, for example, "I read" can be "Yo leo" or simply "Leo." We can't omit the "-o" ending just because we've included the pronoun "yo" for emphasis; likewise, we cannot exclude the indirect object clitic pronoun "les" just because we've included "a ustedes" for emphasis or clarification.
Once we reach this level in Spanish, we need to forget about word-for-word translation and try to move sentences though the "nonverbal meaning" sections of our brain. "Why" isn't a helpful question if you're asking, "Why isn't there a one-to-one correspondence of English to Spanish words?"
Sidenote: I don't like the term "clitic pronoun" and I don't like the fact that there's a space between the so-called "pronoun" and the verb; if the Spanish language had been recently discovered by anthropological linguists, rather than having a documented descent from Latin to the present day, we would have very different spelling conventions & grammatical terminology. A "clitic" is a "prefix and/or suffix," it's not really its own word.
Thank you undeadgoat and everyone else here who's so helpful to those of us who are just learning Spanish. Every language has its "quirks," which are really just incomparable differences between languages and are so difficult for new learners to absorb. But absorb we must, without too much concern with the whys and wherefores.
Hola vandermonde. Como tú lo dices, el uso es opcional a partir del contexto, pero en ocasiones es necesario aclarar el pronombre porque no es obvio.
En este caso no hay un contexto que te permita saber a quien le está leyendo el menú por eso creo que Doulingo lo aclara, ya que la frase podría terminar de diferentes maneras: "ella les lee un menú A USTEDES", ella les lee un menú A ELLOS", ella les lee un menú a ELLAS, ella les lee un menú a LOS NIÑOS, etc.