Button with the key symbol on it.

That's the button to activate or deactivate the SKS. With the button in the out position the smart key system is active.

 

That button is used to disable the smart key function. I used it last week when I left the prius in the garage for 5 days. We were on vacation. This is to save power drain on the 12volt battery. The smart key transmitters get turned off. So it's a "vacation" switch.

 

Another use of the switch is for when you want to leave an SKS keyfob in the car, but still lock it up. I do this occasionally when I go running, and I don't want to risk losing a $200 key on the trail. So the drill is hide the keyfob inside the car, turn off the switch, and lock the doors with a mechanical key. Mechanical keys are available anywhere keys are made, for about $2 (Gen2 - Gen3 is a lot more, and it doesn't have the switch).