Link cloaking is the practice of hiding the actual URL of a link from your visitors or search engines. When you hover over a link with your mouse, you can see in the bottom left of your browser where the link leads to. With Daisycon links, you see the affiliate link you are using. Some publishers prefer not to have this visible to the visitor or search engines because too many outgoing links can negatively impact your SEO. Therefore, they choose to apply link cloaking. This can be done in various ways.
The most common method is that publishers place an extra (virtual) intermediate page on their site. When the visitor clicks on the link, they first go to the intermediate page and are then quickly redirected to the affiliate link (and then to the advertiser).
A link often looks like this:
www.affiliatewebsite.nl/out/advertisername/
The visitor sees a 'nice link' and the search engine thinks you are linking within the website.
For platforms like WordPress, there are various plugins available that allow you to easily apply link cloaking.