As for the switch itself, you can turn it on and off by pushing the button at the the bottom, or dim things up and down by running your finger over the touch-sensitive groove in the center. LED indicator lights will illuminate as you go, and they'll remain on after the switch is off to let you know how bright it will be when you turn it back on.
What's Away Mode? Glad you asked. It's a new feature that sets the dimmer to turn on and off automatically while you're gone in order to fool people into thinking you're home when you're not. When it's activated, the lightbar at the bottom of the switch will shine orange during those random lighting changes.