GitHub's feature "People you know" allows users to discover if any of their friends are aware of a new project by showing how many people they follow have starred that repository. Additionally, it provides insights into the connections within their network by displaying who is following or being followed by others they know, enhancing the social discovery aspect of GitHub projects. This feature, highlighted by Andrew Nesbitt, enriches the user experience by integrating social elements into the exploration of open-source projects.