If you are asking what is this, we wouldn’t blame you. What it will do for you is secure your accounts from easy hacking.
We recommend you put it in place on your email and IT accounts (e.g. Gmail, office 365 etc.).
For instance, let’s say you have a Gmail account for your personal or work email. You log onto it with a password and get in. What if someone can guess your password, or has hacked you? Alternatively, if when you go to login the Gmail sends you a text message and gives you a code to put in, which you then do as well as your password, how secure does that sound. Read more about it here on Microsoft’s blog