info mostra ls:
Following the file mode bits is a single character that specifies
whether an alternate access method such as an access control list
applies to the file. When the character following the file mode
bits is a space, there is no alternate access method. When it is
a printing character, then there is such a method.
GNU 'ls' uses a '.' character to indicate a file with an SELinux
security context, but no other alternate access method.
A file with any other combination of alternate access methods is
marked with a '+' character.