<podcast:season>
Structure, so you can start at the beginning
Season and episode numbers let a show state its own structure instead of leaving apps to infer it from publication dates. For a serialized show that matters enormously: without it, a new listener opening a forty-episode narrative series is shown the ending first. With it, seasons appear as named seasons, episodes sort in the order they were meant to be heard, and "start at the beginning" becomes a thing an app can actually offer.
What you get as a listener
Serialized shows sort correctly and named seasons appear as named seasons, so you are not guessing which of forty episodes is first.
What the show does
Number your seasons and episodes explicitly rather than relying on publication date.
In the app
Episode detail · season and episode numbering