Why is there the possibility to approve and block a user, this seems to be redundant?

A user will be automatically permanently blocked if there have been too many incorrect login attempts on the RetailVista website. First, there will be a temporary block of 15 minutes, but after a repeated number of incorrect attempts, the user account will be permanently blocked. 

In the cash register, it is desired that employees who are no longer employed are no longer shown in the login screen. However, if the option 'Blocked' is used for that, the consequence would be that after sufficient incorrect logins on the website, the user will also disappear from the cash register login screen. That is highly undesirable.

The 'Approve' option is intended to de-approve a user who is no longer employed. By doing so, the user will disappear from the cash register login screen. By only blocking a departed employee, they will remain visible in the cash register screen.