This is a volunteer page. To edit it, browse to the slug 'volunteer' in the Control Panel. You can edit this content in the Basics tab under 'Volunteer settings' (look for the field labeled 'Intro'). You can also customize the message users receive upon signing up in the 'Autoresponse' tab.
Set who receives notification of a new volunteer in the 'Followers' tab by adding a user within your organization as a Follower to this page.