When publishing your podcast, you can mark your podcast and individual episodes as "explicit", and individual episodes can be marked as "clean".
Per Apple's iTunes guidelines, "explicit" means "has explicit or adult content." The actual guidelines are vague, and so we encourage content creators to mark questionable content as "explicit" to avoid being penalized by Apple or Google.
If your podcast is marked as "explicit", episodes will automatically inherit the explicit flag. However, you can also individually mark episodes as "clean", which flags them to Google and Apple as containing no explicit or adult content. This overrides the flag on the podcast itself for only that episode.