I looked at the explanation in the apache.org site but it didn’t explained in a way I can understand. I found some info here .htaccess File Options -Indexes on Subdirectories bu
-Indexes supresses the possibilty of directly listing files in a directory where no DirectoryIndex is set.
Assume a httpd DirectoryIndex set to: DirectoryIndex index.html index.php
.
If you have no file in your RootDirectory according to the DirectoryIndex httpd (in this example index.html and index.php) variable, your directory contents will be listed when +Indexes ist set. Your directory contents will never be displayed when -Indexes is set.
The Indexes option sets whether you can "browse" the directory or not. If indexes is set to plus, and the directory has no index.html or index.php (of whatever) file, it will show the contents of the directory just like your filemanager would do. So if there are ten images in there, it simply shows them as a list with links to the actual image. You can click them and open them.
Most of the time this is not what you want. You don't want others to see what is inside that folder. So then you turn it off with -Indexes.
Here you can see an example of an open dir, as they are called: http://www.ecoutetpartage.fr/images/