By adding a display name, a subscriber will have the option to remain subscribed to a specific list when they attempt to unsubscribe in a campaign.
Your display names can be different than your internal list names.
Note: The label doesn't need to match your actual list name. Specify a public name that makes sense to your subscribers.
Now, whenever anyone clicks Unsubscribe from your mailings, they will see a list of subscriber lists they can remain subscribed to.