https://support.google.com/webmasters/answer/35255?hl=en
The Content Keywords page lists the most significant keywords and their variants Google found when crawling your site. When reviewed along with the Search Queries report and your site's listing in actual search results for your targeted keywords, it provides insight into how Google is interpreting the content of your site.
The significance of each keyword reflects how often it's found on your site's pages. Click each keyword to see a sampling of pages on which it appears. Both keywords and their variants are listed in order of frequency of appearance.
If unexpected keywords, such as "Viagra", appear on this page, this could be a sign that your site has been hacked.
Do you want to provide a URL? Google search a page and view the cached version, it definitely sounds like something is injecting these words and likely links as well.