Content Type Hub is part of Managed Meta Data Service and was introduced into SharePoint to share the Content Types across the site collections and web applications. It was introduced in SharePoint 2010 and now its available in SharePoint 2013 and Office365.
I found this beautiful article to explain how to configure a Content Type Hub to share Content Type across other site collections and web applications:
http://sharepoint-community.net/profiles/blogs/understanding-content-type-hub-cth-in-sharepoint-2013
Note: Its already configured for you in Office365 under http://MyOffice365/sites/contentTypeHub.
