Within Global Office, you will be able to setup your tags and then choose which parts of the site they can be used in (web pages, news, documents).
When adding an item to your website you will be able to select tags that are relevant to that document.
Filter by tags
Your news section in an ideal way of using tags as the side menu can automatically show tags that contain news stories. Clicking on these tags will then filter out news stories that have that tag.
See tagging being used within the News Section of the Diocese of Bristol website.
Filter Homepage Content
Your homepage can be setup so it only pulls in events and articles that have certain tags giving you control on the content that you want visitors to see.