Understanding Opera's Icons
David asked about the Opera UI icons. I assume you mean the icons on the various toolbars.
The easiest way to find out what they are is to right click on the toolbar and select either Images and text below
or Images and Text on Right
as shown in this image.
If you use Windows XP, you may also find the the icons on the Main Bar only show the text label when you hover them. This feature can be disabled by right clicking on the Main Bar, then choosing the Skin
sub-menu, and then the UN-check the option for Special Effects
.