Social Networks are all about influencers. These are individuals or brands that have a great reach. A repin or a like from them could help you broaden your reach and grow your audience.
It is important to know whose these influencers so that you can try and get their attention by posting content that they would like and repin. This insight tells you who your top influencers are based on their follower count and their reach. It also shows additional metrics about the influencer like the number of boards and Pins they have.