netmeg - 1:35 pm on Jan 23, 2013 (gmt 0)
You can select your site's primary language during the application process. If you're approved, AdSense will serve relevant ads to your pages in the appropriate language, even if your site contains multiple supported languages.
Please also be aware that placing the AdSense code on pages with content primarily in an unsupported language is not permitted by the AdSense program policies.
If there is significant content in an unsupported language, Google may not be able to tell if it's inappropriate content. They probably don't want to take the extra trouble to find out.