How to Give Commands with Mac Function Keys
Part of the Switching to a Mac For Dummies Cheat Sheet
A Mac keyboard has function keys, just like a Windows keyboard, but the keys likely issue different commands in Mac OS X than in Windows. On a Mac, the commands assigned to function keys vary by the keyboard's size and manufacturer. Check Keyboard and Mission Control in System Preferences for your settings. The table shows typical default commands for function keys in Mac OS X Lion.
(Note: These commands work only on Apple-labeled keyboards, except for the Turn on VoiceOver command, which works on any keyboard.)