Edit Menu
Undo
Will undo many last actions. Does not work for statistical tests or plots which do not in general perform tasks which are important to reverse.

Cut
Copies the selection to the clipboard where it is stored (until something else is Cut or Copied) and removes the selection from the active window.

Copy & Others
As for Cut but does not remove the selection from the active window. The commands will alter depending upon the nature of the current selection.

Paste & Others
Places the clipboard's contents into the active window at the location of the current selection. If the selection contains some other information then this is erased by the pasted data. The commands alter according to the nature of the information on the clipboard and the type of the active window.

Clear
Deletes the selection without replacing the clipboard's contents.

Select All
Will select all of the data in the current window, be it the spreadsheet, graph or results windows.

Show Clipboard
This will show a window with the current contents of the system wide clipboard and its type.