Almost every account you have probably has multi-factor authentication on it, whether you are familiar with the term or not. When you log into your bank's website and they text you a code on your mobile phone asking you to verify a code they sent, that is multi-factor authentication. It is an additional layer of authentication verifying that you are who you say you are when trying to login to your account. The most common accounts that we recommend having multi-factor authentication setup on is financial sites, banking sites, and Office 365.
A feature about multi-factor authentication that most people don't realize, is that it can act as an alert if someone were to gain access to your password. For example, if you are not near your computer and you get an alert on your phone requesting the code to log in, you would know that your password may have been compromised. This extra layer of security lets you know when your password has been obtained and you need to change it.