In addition to your username and password, you’ll enter a code that Google will send you via text or voice message upon signing in.
Why you should use 2-step verification
2-step verification drastically reduces the chances of having the personal information in your Google account stolen by someone else. Why? Because hackers would have to not only get your password and your username, they’d have to get a hold of your phone.
The verification code can be generated by a number of methods, including SMS TXT, Authenticator App, FIDO keys (USB “key”). So you can select what works best for you.
Find out more: Google Apps 2-Step Verification