Microsoft is deploying an update to SharePoint Online to redesign the so called SharePoint Sites page – known as the SharePoint directory managed by administrators to push SharePoint sites and SharePoint workloads to propose you other sites to follow – to a new SharePoint Home.
Accessing this new SharePoint Home is easy, administrators and end-user has nothing to do. The “old” SharePoint Sites tile is being renamed from Site to SharePoint
Then, the first time you access the new Home, you will a quick welcome deck to help you use this new SharePoint Home
Then you got the new home, showing your recent activities, promoted sites (pushed in the left side)…
Last point, the URL is also being updated from https://<your tenant>-my.sharepoint.com/personal/<user>/Social/Sites.aspx to https://<your tenant>.sharepoint.com/_layouts/15/sharepoint.aspx
NOTE you may have some users in your tenant not getting yet the new SharePoint Home experience while others have; this is just because of the update deployment, it will come