Trusted contacts are friends you can reach out to if you ever need help getting into your Facebook account (ex: you forget your Facebook password and can’t get into your email account to reset it).
After you set up trusted contacts, next time you can’t get into your account your trusted contacts can access special, one-time security codes from Facebook via a URL. You can then call your friends to get the security codes and use those codes to access your account.
To add trusted contacts to your account:
To edit or remove trusted contacts from your account, follow steps 1 through 3 and click Edit next to your trusted contacts.