Icons and symbols on the screen

From Grokdoc

If you have a graphical screen, (that is normal in most cases) you most likely will find explanations for all the objects on the screen if you look for documentation for KDE, gnome, X11.

Icons and symbols may differ a little bit, depending on the distribution, your personal settings, and perhaps your system administrators personal preferences.

If you are using KDE or Gnome I think you can enable an option called 'Show tooltips' or something similar. If you do that, a small description of the object will appear keeping the mouse on the object for a few seconds. (I'm not 100% sure about this though, correct me if I'm wrong)