From what I gathered on the reveal, basically they allow you to re obtain any exotics you already had (lets say you deleted some for space or by accident) you can go to that screen and re "purchase" that exotic, some will have updated stats, but this exotics you "re purchase" will have all the progress lost so you will have to level them back up.

Omg that's so cool

Well that is what I gathered so if it works that way it will be pretty neat. There will be a similar setting for emblems and shaders where you will be able to delete them to free up space and retrieve them any time you want from one of the in game terminals they will have that way you can collect all of them as well as they will appear as a collection.