The n- is used with the noun class 9/10 (the N-class). I think that's used as the standard answer to greetings because habari is in this class, so you say habari nzuri (good news) but mtu mzuri (good person), watu wazuri (good people), kitanda kizuri (good bed), vitanda vizuri (good beds) and jina zuri (good name), majina mazuri (good names).
I think they're teaching us that here because they have to pick one of them and the n- form is the one we'll be using as a reply to greeting phrases. The n-form might be kind of a default option as well, for all I know, because the n class seems to be, from what I've seen, kind of a default for unknown inanimate things.
When hovering my mouse over 'nzuri', one of the translations is 'beautiful'. Yet when I answer 'beautiful', it is false and suggests 'Good' as the right answer.
I'm guessing that this is the more formal way of replying as opposed to "poa", which I'd assume is the slang term like (cool)?
Is this the best way to learn Swahili on your own? Is there any better resource(s)?
Is "nzuri" an acceptable answer to the greetings we learned in this lesson? Like -Habari za nyumbani? (How is your home?) -Nzuri! (Good)
I have no background in Swahili so maybe this is a silly question, but what's the difference between safi and nzuri? In Duo both are translated to mean good. Thank you.