Opera Help

Tooltips

These are small, useful boxes that display to provide you with relevant extra information when you hover certain parts of the Opera browser or webpages with your mouse. For example, when you hover the buttons on the address bar, a small box displays under your mouse cursor that tells you what that button is, and may provide any relevant keyboard shortcuts you can use instead.

Turn off or on

To change this setting, go to Preferences > Advanced > Browsing and either uncheck "Show tooltips" if you do not want to see them, or check it to display them.