Twitter has added support for multiple security keys to accounts with two-factor authentication (2FA) enabled for logging into the social network’s web interface and mobile apps. The company also announced a future option for 2FA-enabled accounts to use security keys as the primary authentication method while having all other login methods disabled. 2FA is an additional security layer for Twitter accounts that requires users to use a security key or enter a code on top of only entering a password to authenticate successfully. To turn on 2FA on your Twitter account, you will have to go to your profile menu into Settings and Privacy.
Source: https://www.bleepingcomputer.com/news/security/twitter-now-supports-multiple-2fa-security-keys-on-mobile-and-web/