Joomla articles can be given one or more 'Tag'.
A menu item can be created, using the 'Tags' component, which then lists the tags used throughout your Joomla!® website.
That Tags component menuitem is what you see here on this page.
Select a tag and you will be presented with a list of all the articles that have been assigned the repective tag.
So, for example, if you want to know what articles have been assigned the tag 'Joomla' - select the 'Joomla' tag from the list below.
For some tags there may only be a result of one article, for other tags there could be a result of more than one article (multiple articles).