The 2-step verification is a feature wherein aside from the password, a 6-digit verification code from the Google Authenticator app on your smart device is also required to login.

Now, each time you log into the account you've connected with Google Authenticator, the account will ask you to enter a six-digit verification code.

Google Authenticator is a two-step verification software used to keep your Google account and its related apps and programs more secure.