These are links that use the nofollow attribute to tell the search engine bots not to follow the link to crawl and index that website. However, website visitors can still click on the link and go to the other website. This is used to retain more value on the website where the nofollow link is located and not pass any authority to that website. This is what a nofollow attribute looks like.
<a href=”http://www.website.com/” rel=”nofollow”>Click here</a>