Wordsworth's use of imagery and language helps the reader to imagine all of the sights that he is talking about. In the second stanza of the poem, he is saying that this woman who is singing in the field as she reaps the grain, has a voice that is sweeter than nightingales or cuckoo-birds. He says her voice is sweeter than those birds might have been to great Arabian armies resting in the shade, or to anyone hearing the bird across the oceans. So, as I read this stanza, it is easy to imagine a group of travel-weary Arabian soldiers, tired and thirsty, resting in the shade of a sand-dune on their journey. And as they rest there, they hear the sweet song of a nightingale. That would be a wonderful sound to hear on a long, hard journey in the desert. So Wordsworth helps us to conjure to mind how wonderful and sweet this woman's song is, by helping us to imagine the soldiers resting and enjoying that nightingale's song.