I see you are doing many languages on Duolingo. Is it the first time you see non-sense sentences from Duolingo? we see them all the time (i think they are probably part of real conversations from movies or books). I was surprised when I started with Duolingo 2 years ago but now... I just get a long however non-sensical that might be
But this isn't a sentence, TJ_Q8. It's a perfectly good phrase. We've often had phrases. And I think it's useful of Duolingo to give us little exercises where we can't use the context as a crutch. You may like to know that "nonsense" doesn't have a hyphen, and the phrase is "get along", not "get a long", which is in need of a noun for the adjective to modify.