Removing the endorsement of a profile, page, or post, which prevents further notifications or interaction with the object.

Why Do You Need to Know About Unlikes?

Once a user unlikes a Page, they will no longer see updates from that Page in their Newsfeed. Users might unlike a Page if they don't like the content they see posted, don't often interact with the Page, find the Page annoying, or for other reasons. 

Marketers can see how many users have unliked their Page within the Facebook Insights dashboard. A high volume of unlikes may mean the brand needs to reevaluate their Facebook posting strategy.

Facebook Unlikes show the number of people who have chosen not to communicate with the brand.