During a Season roll-over (which occurs after a Season has ended), your Seasonal heroes, inventory, shared stash, and Paragon experience will be transferred to your non-Seasonal profile.
Normal heroes, inventory, shared stash, and Paragon experience will transfer to your Normal non-Seasonal profile. Similarly, Hardcore heroes, inventory, shared stash, and Paragon experience will transfer to your Hardcore non-Seasonal profile.
Heroes: At the end of a Season, your Seasonal heroes will become non-Seasonal heroes. They will appear in your normal roster. Any items, equipped or in the heros inventory, will roll-over with the hero itself.
Shared Stash: Items in your Seasonal heroes shared stash will be mailed to your Normal/Hardcore non-Seasonal profile. These items can be retrieved by entering a game on any non-Seasonal hero and clicking on the mail icon located in the lower left of your screen.
Currency: Gold will be automatically transferred from your Seasonal profile to your non-Seasonal profile. Ditto for Blood Shards.
Paragon Experience: Paragon experience earned during a Season will transfer over directly without any additional involvement required from players. All Paragon experience will transfer, with experience gained by Normal Seasonal heroes going to the accounts Normal non-Seasonal profile, and experience gained by Hardcore Seasonal characters going to the accounts Hardcore non-Seasonal profile. (Note: Non-Paragon experience will not transfer.)
Artisans and Crafting Plans: If your Seasonal Artisans are a higher level than your non-Seasonal Artisans, their level will transfer at the end of the season to your non-Seasonal profile. Any recipes you have on your Seasonal Artisans that are not available to your non-Seasonal Artisans will be transferred as well.
Hope this helps!