The Scheduled tab in the Command Center is where you go to check any scheduled emails that are queued for a later date.
If you scheduled an email to go out at a later date and need to edit or delete it, the Scheduled tab would be the place to do so.
This Scheduled tab is also where your Campaign follow-ups are stored until they're ready to be sent. So, if you used a campaign with three steps, after you send the first one, the second scheduled email will appear. After the second is sent, the third will appear.
Scheduled emails will be bubbled up to the Command Center homepage.