This page shows the associated people in the group selected at the top right of the page. If you have the Group View set to All groups, this will show every person across groups associated with the account instead of only people from a specific group. On this page, you can:
Edit People - Click on the box next to the name of the person you would like to edit and select the edit button (pencil icon).
Invite People - Use the gold "+" button in the top right of the People table and fill out their name, email address, which group you want them associated with, their role, and which apiaries/sites to share with them.