Two-factor authentication

Two-factor authentication is an extra layer of security for your Apple Account designed to ensure that you’re the only person who can access your account, even if someone knows your password.

To see whether your Apple Account has two-factor authentication turned on, choose Apple menu  > System Settings, then click your name in the sidebar. Click Password & Security, then turn on Two-Factor Authentication.

See the Apple Support article Two-factor authentication for your Apple Account.