If the final character is an at sign ( then it signifies that the file or folder has extended file attributes relating to security, giving certain apps (like Finder) persistent file access. These levels are always shown in that order, so for instance:
You’ll see letters here, too, such as r (read), w (write), and x (execute). The first group shows the access levels for the file/folder owner (1), the middle group shows group permissions (2), and the final three shows permissions for any other users (3).
The next nine characters are split into groups of three.