Page Unlikes: The number of clicks that Unlike a Page. 

Post Unlikes: The number of clicks that Unlike a Page from a piece of content in the newsfeed. 

Hide Posts: The number of clicks that hide a piece of content from a Page. 

Report Spam: The number of clicks that report an object as spam.

For more information on Facebook metrics, please refer to the following FB developer resource: https://developers.facebook.com/docs/graph-api/reference/v20.0/insights