Add some content to the callout.
Maybe a link?
Or a warning?
Close the callout if it is in your way, click the X.
The alert is also called a 'callout'. It is supposed to have a fixed position (not here on this page, that would interfere with the page heading). In the downloadable file it will be sitting near the top right corner of a page.The position can of course be changed in the Position section on the styles pane. And pictures can also be displayed in an alert.
Such an alert is often used to display something important, like a Cookie warning, an offer, or any kind of 'nagging screens' that can be clicked on to disappear.
Hot tip: It shouldn't be used too frequently.