The ads are the source of revenue earned for the content that has been viewed.
When you publish your work on hubpages the pages that have your content will display the ads being placed on those pages.
The ads need to be displayed in order to have earnings. This is why the pages with your content will always include the ads.
Feel free to ask more questions in the comments on my hub:
Each user can only post one answer on this page, but I can answer other questions if you post it on the page that has my article.