In this screen, you can assign your button as a:

Keystroke — Assign a single key press, or a key press with modifiers.
Multi Key — Assign a "macro'd" series of keystrokes. (NOTE: You can set up these macros to function both with and without recorded time delays.)
Text Block — Create a block of text to be typed out when the key is pressed (either with or without Unicode support).
Mouse Functions — Assign a button on your mouse to use any of the available mouse button functions.
Media — Set a mouse button to function like a media key you'd typically find on a keyboard.
Hotkeys — Use a pre-defined keystroke command.
Shortcut — Assign a button to launch a file/folder/drive on your computer.
Function — Assign a button to act like a Microsoft function button (ex. to open your web browser).