Lets explain what an object's ACL is. I will use an example to best explain this. Let's suppose that user Bob would want to access a folder in a Windows environment. What supposedly will happen is that Windows will need to determine whether Bob has rights to access the folder or not. In order to do this, an ACE with the security identity of John will be created. These ACEs are the ones that grant John access to the folder and the ACLs of this particular folder that John is trying to access is a list of permissions of everyone who is allowed to access this folder. What this folder will do is the to compare the security identity of John with the folders ACL and determine whether John has Full control of the folder or not.
By right clicking the folder and selecting the security tab, John will be in a position to see a list of the permissions (ACLs) granted to him by the folder.
