two-factor authentication (2FA)

Two-factor authentication (2FA), sometimes referred to as two-step verification or dual factor authentication, is a security process in which the user provides two different authentication factors to verify themselves to better protect both the user's credentials and the resources the user can access. Two-factor authentication provides a higher level of assurance 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 users providing a password as well as a second factor, usually either a security token or a biometric factor like a fingerprint or facial scan.

Short Summary: Two-factor authentication (2FA) give you extra passwords login / signin security for your mobile and internet web account eg apps like Facebook, Instagram, Twitter, Gmail - Yahoo Mail etc. 

To access 2FA on your Social Apps Account, it is usually located in Settings - Security - Privacy.

Lastly you can use Authenticating Apps like Authy or Google Authentication Apps to secure Your access. This way your accounts can't be hacked by hackers.

Source: searchsecurity.techtarget