SHE DWELT AMONG THE UNTRODDEN WAYS

From the title the reader understands that the text speaks of a woman who lived near the river Dove. At the same time, considering the layout the reader can understand  the poem is a ballad since it is arranged into three stanzas. The stanzas are quatrains.
The first stanza introduces Lucy as a good girl who lives in solitude near the source of the River Dove.
The second stanza tells the reader that Lucy was a beautiful and rare creature. Indeed, she is compared to a violet difficult to be seen. Lucy was not known by a lot of people and she lives hidden in a distant place.
The third stanza is about Lucy's death, the few people who knew her  and conveys the speaking voice's loss of Lucy. He misses her.
He says that Lucy is now buried in her grave and her lack is a great difference for him.

The rhyme of the ballad is alternate  (what is the function of such stylistic choice?).
The phonological level takes in considerations the alliterations (Is shining in the sky) in the second stanza.
There are some figures of speech for example the run-on-line in the first stanza (The untrodden ways beside...).
In the second stanza there are a metaphor (a violet by a mossy stone), a simile (Fair as a star) and a run-on-line (When only one is shining in the sky). This part does simply make a photo of the text: it does not explain their function they play to add meaning to the text

The poet wants to highlight Lucy's positive figure, telling that she was important for him and he wants to emphasize that even if  Lucy was unknown she was a great person for the speaking voice..