When you add a link inside your content, Yoast SEO provides you with extra settings. These let you choose how search engines should treat that link.
Yoast』s advanced link settings option, when creating or editing a link in WordPress.
When you select these options, we enhance the HTML markup of your links to include the relevant instructions (or attributes).
Link options
「Search engines should ignore this link」
Enabling this option adds a nofollow attribute to the link. E.g:
Before: your link
After: your link.
Depending on the search engine, this may either discourage them from following the link, or, discourage them from 『rewarding』 the link (e.g., by passing PageRank or other signals through it).
It』s good practice to enable this setting on links which lead to third-party websites which you don』t endorse or trust, and on any paid/sponsored or otherwise incentivized link.
Note that, despite the name, the nofollow attribute doesn』t necessarily mean that search engines won』t still follow the link.
「This is a sponsored link or advert」
Enabling this option adds a sponsored attribute and a nofollow attribute to the link. E.g:
Before: your link
After: your link.
It helps them to understand which links may be paid (or incentivized) placements.
Note that selecting this setting will also automatically select the 「Search engines should ignore this link」 setting. We do this in order to comply with search engine guidelines, and because some search engines don』t support/understand the sponsored attribute.