Office 365 Multi Factor authentication (MFA) provides additional security for your user account. MFA is a method of verifying who you are that requires more than just a username and password. Sign in can only be completed once you have acknowledged a sign in verification process either by text message, voice call or via a smartphone authenticator app.
For more information and FAQs regarding Multi Factor Authentication, visit: https://fxplus.ac.uk/it-services/multi-factor-authentication-mfa/.