This is a strong authentication plugin. You have to fill a second field, kind of password but this one comes from a printed card you own (FR/EN).
This kind of authencation is called "Strong Authentication", strong authentication is associated with at least two-factor authentication. Your usual password is the first and only factor, this plugin adds an external factor : a MSL Secure Card. Now, you have 2 secure factors to log in.
When someone wants to log in any account, he has to fill the username, password and now a "MSL Code" field. This code is printed on a card (you have to print it) and contains a code from A1 to H8. Without this code, he can not log in!
Every blog which needs to improve its login's security.