The speaker describes something she sees as taking a "Route of Evanescence." "Evanescence," a difficult, five-dollar, SAT-type word. It means disappearance or fading, so the speaker seems to be watching something that carves out a fading route, or path.
This mysterious being or event is either accompanied by or looks like a wheel—the image of a train or a bicycle comes to mind. Whatever she's watching, it's fast—seeming to flash in and out of sight with its circular motion.
A Resonance of Emerald – A Rush of Cochineal –
Here the speaker zooms in on two colors that she notices. Rather than just describing what she's seeing as simply "green and red," the speaker uses more precise shades of these colors in order to make the images that much more vivid and specific. That's nice of her, don't you think?
Not only does "Emerald" immediately present a certain kind of green in the reader's mind, it also reminds us at Shmoop of jewelry, and a certain royal quality, making whatever the speaker is seeing that much more awesome.
That awesomeness is something that sticks with you, too. The use of the word "Resonance" highlights how this royal green color stays in her mind.
"Cochineal" is, for most readers, an extremely difficult, foreign word. It can refer to a crimson-colored dye as well as the insect from which this color is derived. (Fun fact: just the females are used in producing the dye.) The use of this extremely difficult, specialized word gives the speaker some authority, because it shows that she's knowledgeable enough about color to be able to specify this exact shade.
With "Rush," the speaker continues to emphasize the speed of what she is looking at.