Two-factor authentication is a method of identifying a user by requesting two different types of authentication data, which provides more effective account protection from unauthorized access.
In practice it usually looks like this: the first part is the login and password, the second is the special code that is generated using a mobile application that is installed on your smartphone. When you sign up into your account you enter your login and password, then the system requests the code to give you an access your account. The code is generated in a special application which you install on your smartphone.
Thus two-factor authentication gives you two layers of security to prevent unauthorised access: even if the fraudsters gain access to your login and password, they will not be able to log into your account because only you will have a codeon your mobile phone.