"Canto" is the Italian word for "song." It comes from classical Italian poetry, where poets would divide long poems up according to "cantos," much like novels have chapters. By using the word "canto," Pound is connecting himself to a classic tradition of European poetry.
More specifically, the most famous poet to divide his works into cantos is Dante Alighieri, the Italian master who wrote such famous poems as Inferno (which, by the way, they made a video game of) and Purgatorio. In these poems, Dante follows the main character Virgil down into hell to explore the darkest depths of the human soul. That's sort of like what Pound is doing by following Odysseus into the underworld. So in this sense, both Pound and Alighieri are trying to express the dark side of humanity in poetic form, maybe so they can come to terms with it and find a way to make it beautiful.
Finally, the fact that we're specifically reading "Canto II" tells us that this poem is picking up where "Canto I" left off. The fact that this Canto was first published in a volume called A Draft of XXX Cantos tells us that we have at least 28 more to go, so we're still in the early stages of Pound feeling his way into this long, long project. Did we mention that The Cantos as a whole are really long? Pack a lunch if you plan on tackling all of them.