Hotlink protection prevents other websites from directly linking to your files (typically images) of your website. Enabling Hotlink protection on your website will not allow other websites to load your images and other media files on their website.
This is one of the popular tricks to prevent unauthorized usage of copyrighted images and bandwidth of your server.
Hotlink protection can be enabled from the cPanel control panel.
cPanel will check the URL of the request, and if it is coming from any other domain name, the images will not be rendered.
Please refer to the video tutorial on How to setup hotlink protection in cPanel.