Breakdown of Nos fascina que ustedes aprendan el idioma.
ustedes
you (plural)
el idioma
the language
aprender
to learn
que
that / than
Questions & Answers about Nos fascina que ustedes aprendan el idioma.
Why is it aprendan (subjunctive) instead of aprenden?
Why is the verb fascina singular when nos (us) is plural?
Fascinar works exactly like gustar. The pronoun nos tells us who is fascinated, but it isn't the subject. The actual subject of the verb is the entire action that follows: que ustedes aprendan el idioma. Since that entire phrase is treated as a single concept, the verb takes the singular form fascina.
Can I just use the infinitive and say Nos fascina ustedes aprender?
No, because the person feeling the emotion (nos) is different from the person doing the action (ustedes). When there is a subject change like this with verbs of emotion, you must use que followed by a conjugated subjunctive verb. You would only use the infinitive if the subjects were the same, for example: Nos fascina aprender el idioma (We are fascinated to learn the language).
Why is it el idioma? Doesn't the "-a" ending usually make it feminine?