Module access vs roles

hi experts
what is benefit of using the module access? Because I noted that when the user have user account role (for example) I could not prevent him from access the account module even the account module access unchecked. and I could not let him access the account module if dose not has account role.
best regards,

@dufani1

When you uncheck any module for a particular User in Module Access it means that the User do not have that particular module on his/her Dash Board. But if the User has Roles that can access those modules then they can

Shachi I see that the module access option means nothing or useless… if I am wrong please explain why?
Regards,