Two-factor authentication means a password alone isn't enough to log in — a second, time-limited code is required too, so a stolen or guessed password on its own can't get someone into your account.
Enable it from your account settings. E-DOB's 2FA is email-based: after entering your password, a one-time code is sent to your registered email address, which you enter to complete login.
2FA is optional for most accounts but mandatory for platform administrator accounts specifically — administrators can see and change the most, so they're held to the higher standard by default rather than by choice.