The Control Panel lets you manage the subdomains that you delegated to Adobe Campaign. You can view your subdomains, as well as request renewal of their certificates. More actions will be available from this card with upcoming releases.
More details on subdomain delegation is available here (Yes, it applies to Campaign Standard as well).
The Subdomains and Certificates card allows you to see which ones of your subdomains and associated subdomains hosting your landing pages and resources with SSL certificates installed on them. You can also easily see which subdomains have expiring certificates so that you can anticipate their expiration. If a certificate is about to expire, you can then initiate a Customer Care request with all required information to renew the certificate and ensure proper functioning of your instance.