Because guata has a special construction in the language. 'It is liked by me.'. Me gusta
I am probably being thick but I don't really understand nos. I presumed it was short for nosotros but I have seen a few sentences that say Nosotros nos !!!!!
Nos is the object pronoun of nosotros. That means nosotros is "we" in English, and nos is "us".
Remember that gustar works a bit backwards - the subject is the thing that's being liked, and the object is who does the liking. Gustar works closer to "to please". "Nos gusta tocar la guitarra" - "To us, playing the guitar is pleasing."
The subject (the part that determines the conjugation of the verb) is tocar here, which is singular. Nos is the object.
the correct answer provided to me was : We like to play the guitar so much. where does the so come from?
[We like to play the guitar much] isn't good English, so sometimes things like so are added in.
I recently had the sentence "Mi abuela me ama mucho." [My grandmother loves me much] needs something to make it sound good, and Duo's translation was "My grandmother loves me very much.
I was using the movable words (not typing), and it seemed to think guitar was spelled wrong... yet the correct way was the same as what it was?? It underlined the "ita" in "guitar". I'm not sure what happened, but I flagged it.
Duo has a fun way of correcting a wrong answer. It underlines the wrong word in the answer you gave, but overwrites that with the correct sentence. So you tend to get underlines in seemingly random places.
Mucho is used as an adverb for gustar here, indicating that the liking is done with a high intensity. Most often it's translated as "very much" or "a lot", but "really" works as well.