Your vehicle has an automatic transmission shift lock control system. You have to fully apply your regular brake before you can shift from PARK (P) when the ignition is in ON. See Automatic Transmission Operation .
As a reminder, you will see a message in the Driver Information Center (DIC) that will say PRESS BRAKE BEFORE SHIFT within 15 seconds unless the brake is pressed.
If you cannot shift out of PARK (P), ease pressure on the shift lever - push the shift lever all the way into PARK (P) and release the shift lever button as you maintain brake application. Then press the shift lever button and move the shift lever into the gear you wish.
If you ever hold the brake pedal down but still can't shift out of PARK (P), try this: