"She shows us her house."
Translation:Ella nos muestra su casa.
In the comments for this section a lot of people are saying that these optional clarifications are very unnatural to native speakers. The lessons have indeed been teaching that we can clarify (or emphasise) sentences in this way, but it seems to me that it's best to practice constructing sentences without them.
In this case, there's no ambiguity because 'nos' can only refer to us, so I guess you'd only be adding 'a nosotros' for emphasis and that seems odd to me :)
(Before I start, I'm by no means a native speaker so please correct me if I'm wrong)
First, "su casa" is the direct object (as it follows the transitive verb "muestra"), meaning that the "a" is again rendered unnecessary. "Nos" is the indirect object.
Also, you only use "a" following a verb, when what follows the "a" is a person. Since a house is not a person, you don't use "a" in this case.
If you are using it as we sometimes do when clarifying who the object pronoun refers to (as in saying "él les escribe una nota a ustedes", where "a ustedes" tells us who "les" is referring to), then it's also wrong because "nos" doesn't mean "su casa", it means "nosotros". As others have stated, "nos" only ever means "us" so you rarely need to clarify.
I'm confused about when the verb agrees with the object and when it agrees with the subject. For example: a couple sentences ago "my daughter likes apples" "A mi hija leS gustAN las manzanas" but here it is muestra rather than muestran even though she's showing it to US (pl).
Well, first, your sentence is wrong, it should be like that: "A mi hija le gustAN las manzanas" (and not "leS"). The word "le" means "to her/him etc." which refers to "my daughter". The word "gustan" (from GUSTAR = to like) referd to the apples. Instead saying this sentence I can say: The apples are tasty to my daughter (The meaning stays)
I'll try to show the differences so that you can understand it better:
" to my daughter " = " A mi hija "
" are tasty " = " gustAN "
" (to her) " = " le "
and of course that "apples" is "manzanas".. When you see a phrase you should try to convert it to a phrase with the same meaning, and then do this comparing, OK?
I'm not a native speaker so I hope I succeeded in helping you.... :)