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 menu item 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 respective 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).