When you add this content type to a section (page), it will add a heading "Page Last Updated" along with a date (month, date and year), which is automatically updated for you each time you publish new changes to that page.
Use this content type when you wish to give your users a quick and easy visual indicator exactly how recent or up-to-date your page content is, which is especially useful when timeliness is of utmost importance to the content or to your users.
Navigate to the section where you wish to add this content item. Click "Create content" then select the "Last Modified" content type.
This content type automatically updates the date for you based on when you last saved and approved (last modified and published) a piece of content, but the date will not update when you delete a piece of content.