What is MFA \ 2FA

Multi-factor-authentication (MFA), adds an extra layer of security to your sensitive accounts.. MFA is achieved involves using at least two of the following factors:

Something you know: This is typically a password.
Something you have: This could be a physical authentication device (token), a mobile authentication app, a code sent via SMS, or something similar.
Something you are: This refers to biometric authentication, such as fingerprint or facial recognition.

Most implementation include the use of two factors, usually a password or PIN with a One Time Password sent by text or generated by an app, hence most implementations are actual two-factor-authentication - 2FA. 

Benefits of Using 2FA

As mentioned in the Passwords Management guide - many people use the same password on various services. That means that a single credential exposure incident, can impact multiple accounts.
As we know, even the best passwords can be leaked in a data breach, not to mention, exposed by a sophisticated attacker.

Using 2FA reduces the chances of unauthorized individuals accessing your accounts, even if they have your password.

Knowing that your accounts are well-protected can give you greater peace of mind.

Where Should You Use 2FA

Adding 2FA \ MFA is considered best practice to protect all your sensitive accounts, and especially:
Email accounts
Social media accounts (Facebook, Instagram, etc.)
Online banking accounts
Shopping accounts
Cloud storage accounts.

My advice is to enable 2FA on all services that allow it.

Remember
Never give ANYONE your One Time Password