Permissions are the association of privileges, which are actions that are provided by resources such as a Perforce Chronicle module, to roles. For example, you may want to give users having the member role the privileges to add new categories and associate them with content, but not give them the privilege of managing categories. There are many privileges provided by Chronicle and each activated module can implement its own resources and privileges.
The Manage Permissions screen is where management of privilege and role associations are performed. Privileges are listed vertically in the first column, roles are listed horizontally, representing the grid of possible permission associations. Hover your mouse over each of the numbered callouts to highlight the associated area of the screen.