The /etc/apache2/conf-available directory contains additional configuration files that not associated with a particular module. This directory holds specialized and local configuration files, and links to configuration files set up by other applications.
The configuration files in the conf-available directory are not active unless enabled. The enabled configuration files are listed in the /etc/apache2/conf-enabled directory as links to the corresponding modules in the conf-available directory. To enable a configuration file, the a2enconf command is used, while the a2disconf command is used to disable one.
Here is the content of this directory in Ubuntu: