To use function of cACL you must be logged into as Super Administrator:

Log into the Backend side of your Joomla:

Navigate to the cACL. Once you have logged in, hover over the Sitelink on the top taskbar, scroll down to cACL:

When you have selected the cACL, you will be sent to the Access Menu Item that lists all Administrators. Select an Administrator depending on whether you want to set limitative functions (here is giangnt )

When you have selected the Administrator (giangnt), you will be sent to the cACL screenshot by this Administrator:

Select Tab Site to set limitative elements of Site functions which you want

There are 3 options using to set up limitative elements of Site (Allow; Hide, Restric). For setting up, you select one option colerrative one element of Site. Default is allow for all.

For this example, you do not allowed giangnt to access Statistics and Trash Manager.

After that, you could choose Save task or Cancel task to save or cancel and back the previous page and set up other administrator or if you choose Apply task to Save and continue setting orther limitative functions. 

he Result when giangnt logged into the system:

The following screenshots shows you the end result of selecting limitative elements of  Site to administrator - giangnt . There are some differences betwewn before limitting and after limitting:

Before limitting: giangnt could manage all functions of Site Menu on the system that you allowed.

After limitting: giangnt couldn't manage Statistics and Trash Manager