As you may be aware, Secure Score has been there for a while already, helping you understand your security posture on Office 365 and helping you improving it.
Now, after the release of the new Microsoft Office Security Center (https://security.microsoft.com), Secure Score has moved to a new home hosted in this portal (https://security.microsoft.com/securescore?viewid=overview).
Don’t get worry, if you still use (or have a favorite to) the ‘old’ Secure Score URL (https://securescore.microsoft.com) it still available until end of May and then you will be redirected.
If you use the Security and Compliance portal (https://protection.office.com/) the link (https://go.microsoft.com/fwlink/?linkid=2083668&clcid=0x409) to Secure Score has been update to get you to the new home.
All the existing Secure Score features you know are available.