Hello Soazkaren,
Thanks for the question. Currently, this module is something that can only be installed on VPS or Dedicated server accounts. Installation fee for adding it through our support team would be $25.
Basically, the code will replace or omit certain characters and elements of the website code in order to reduce bandwidth consumption. It also helps the browser to better process a page.
It is recommended only for sites where there is little or no optimization already built into the code. Or, if you have a web page that is also not optimized and receiving lots of traffic. A case where you shouldn't have to use it would be something like a WordPress site that is using caching. An example of where you might want to try it would be a page that was built in a Word processing application and imported over using no compression with images/graphics on the page. If you are curious about how well your webpage performs, try using Gtmetrix. They will grade your site and give you suggestions on how to speed it up, usually without recommending something like the Google Page Speed module.
I hope that helps to clarify your question! Please let us know if you need any further assistance.
Regards,
Arnel C.