To change the language of the website statistics generated by AWStats on a Debian Linux server to e.g. german (de), edit the /etc/awstats/awstats.conf file:
and change the value of the "Lang" variable. To change the languge to e.g. German, cahnge:
The website statistics are generated nightly on a ISPConfig 3 server, so it may take up to 24 hours until the statistics will show up in German language.
Thanks to PlaNet Fox for this FAQ.