Invitation emails will be sent to the listed email addresses. These emails contain a "SIGN UP" button the users can click to set up their account and join your organization.
Check invitation status
People whose invitations have not yet been accepted will display with "Invited" in the "Last active" column.
If necessary, you can delete a pending invitation by clicking the menu button in that row and selecting "Delete invitation".
Update roles
Click the row of the user you wish to manage. This will open the "Edit roles" dialog.