"길의 그편에 나무들이 있습니다."
Translation:There are trees on that side of the street.
Not sure how much this answers your question but to help understand the word order try building the sentence right to left from the verb:
있습니다 - there are/is/exists.
나무들이 있습니다 - there are trees.
그편에 나무들이 있습니다 - there are trees on that side. This could also be rewritten as "on that side there are trees" and, with appropriate context, could probably also be understood as "the trees are on that side".
길의 그편에 나무들이 있습니다 - there are trees on that side of the street. Again this could be rewritten as "on that side of the street there are trees" and again, with appropriate context, can probably also be understood as "the trees are on that side of the street".
From what I can recall from linguistics, in most, if not all, languages statements are always contructed stemming from the verb and Korean is no exception. It just so happens to put everything to the left of the verb
Somebody correct me if I'm wrong, but I would say "나무들은 길의 그편에 있습니다."
Since it sounds like the trees are previously known, the focus of the sentence is on their location, not on their existence, so it makes sense to change from a subject marker (이/가) to a topic marker (은/는).
That is a completely different sentence. "The trees are on that side of the road" imples the trees had been brought up in prior conversation. The correct answer, "there are trees on that side of the road" implies that you are simply pointing out that there are trees there. This should not have been flagged.
I don't recall the word but there is a special word for saying there are many. I saw it in a later lesson.
I do up to level ones so i can open the next lessons. Then i can come back to the earlier lessons. I was anxious to start numbers, family, and past tense. It makes me happier and less frustrated because i am learning a variety of useful words.