Link Ads are advertisements provided by Google Adsense, through which you can monetize your website.
They contain a bunch of text with links to different advertiser’s website. It displays topics prevalent to your content, they are the highest paying because when a user clicks on any of the following topics, it means that the user is interested in the following topic. That’s why advertisers pay higher for links ad to be shown on the publisher’s profile. They are also known as “Pay-Per-Click” ads.
Link Ads target user’s interest and publisher is paid through clicks but not the click by themselves because it leads to invalid click activity and you may get banned from Google Adsense forever.
You should not spam a bunch of links ads on content if it’s not having thorough content.