Aggregated demographics data about the people who like your Page based on the age and gender information they provide in their user profiles.
Male: The number of male users who like your Page.
Female: The number of female users who like your Page.
Age Group: The most prominent age group of users who like your Page.
For more information on Facebook metrics, please refer to the following FB developer resource: https://developers.facebook.com/docs/graph-api/reference/v2.8/insights