Two-Factor Authentication - security process requiring two different authentication methods. Like needing both an ID and a secret handshake to enter a club.
Gmail 2FA requires your password plus a code from your phone to sign in from new devices.
2FA/MFA is an identity feature rather than a single compute/storage service. AWS IAM, Microsoft Entra ID, Google Cloud Identity/Workspace, and OCI IAM all support adding a second factor (app, hardware key, SMS/voice in some cases) on top of a password or SSO sign-in.