It’s called the APIlity Library and it allows interaction with the Google Adwords program:
The APIlity PHP Library provides an object-oriented way to easily access and manage the Google AdWords API from within PHP. This comes along with an abstraction from the SOAP and WSDL details.
Requirements (also from the sourceforge page):
APIlity works both with PHP4 and PHP5 and usually only requires the cURL extension to be installed. This can be done very easily by uncommenting the line; extension=php_curl.dll
in your php.ini file, i.e. remove the semicolon at the beginning of the line. If you are using PHP4, you additionally need to enable the DOM/XML by uncommenting the line; extension=php_domxml.dll
If you don’t manage your server or have (root) access to your php.ini file, then copy/paste the above requirements text and send to your hosting company’s support. They should be able to enable this for you or instruct how to get the proper web hosting plan that would provide this functionality.
References
How to tell if cURL is enabled
How to find the location of the php.ini file on the server where you website is hosted
