It is another tool for your data protection and is used as another security layer after the username and password. If it is activating your verification process will take 2 steps – casual password and verification code which is, technically, this second factor.

Google Authenticator is used and generates 2FA codes. Do not worry, it is not just secure, it is the most secure 2FA configuration ever. When the app is set up it does not need internet access or additional phone verification. Not being associated with your phone number it is immune to any phone number porting attacks.