The Odyssey is one of the oldest extant works of literature still read by contemporary audiences. As with the Iliad, the poem is divided into a full 24 books. It follows the Greek hero Odysseus, king of Ithaca, and his journey home after the Trojan War. It explains all the hardships he faced while trying to return home, so in short: a very long journey.
The meaning behind this quote is that by doing nothing/not practicing, you are not bettering yourself. the only way to better yourself at something is by practicing it.
It means the people in the past did something great and we now receive the benefits. he is urging us not to forget, so that we may leave a positive mark in history.
