The full form of 2fa is Two-factor authentication

Two-factor authentication (2FA), sometimes referred to as two-step verification or dual-factor authentication, is a security process in which users provide two different authentication factors to verify themselves.

2FA is implemented to better protect both a user’s credentials and the resources the user can access. Two-factor authentication provides a higher level of security than authentication methods that depend on single-factor authentication (SFA), in which the user provides only one factor — typically, a password or passcode. Two-factor authentication methods rely on a user providing a password as the first factor and a second, different factor — usually either a security token or a biometric factor, such as a fingerprint or facial scan.

We highly recommend enabling two-factor authentication (2FA) for the following reasons:

• Security!
  2FA increases the security of your account. Even if somebody guesses your password, they won’t be able to access your account.
• Free games!
  2FA is required to claim some free games on the Epic Games Store.
• Gifting!
  2FA is required to send gifts in Fortnite.
• Competing in Fortnite!
  2FA is required for participation in Fortnite competitive events such as the Fortnite World Cup!

Since your account security is a priority for us, we also give players rewards for enabling 2FA. You can check them out here. For more information about what you can do to secure your account,

If a site you use only requires a password to get in and doesn’t offer 2FA, there’s a good chance that it will be eventually be hacked. That doesn’t mean that all 2FA is the same. Several types of two-factor authentication are in use today; some may be stronger or more complex than others, but all offer better protection than passwords alone. Let’s look at the most common forms of 2FA.

see also What does MFA mean? What is the full form of MFA?