The Related Pages module, also seen as Read more, is a Wikia extension that puts a heading at the end of the article content (but still inside of the article content), before the list of categories, with a section named Read more and 3 images that link to other articles that share one category in common with the current article. The format is very similar to the format used by the Wikia's spotlight system promoting other wikis. The image that represent an article is one of the first ones of the article, sometimes not the most relevant one.
It was created only for oasis skin, but when Wikia upgraded to MediaWiki 1.19.X it was activated also on Monobook, and Staff aren't willing to disable it on monobook by default.
For all users on a wiki Edit
This feature can be turned off entirely by requesting that through Special:Contact.
For personal or wiki-wide use Edit
You can disable it through CSS, for example if it's enabled on a particular wiki where you are not an admin or where people prefer it to be enabled.