Have you started driving your new car already? Let's hope NOT.
Anyways, that's not what you asked, so here we go...
P=PARK - the gear selector should be in this position when the car is parked as it typically locks the transmission so that the car cannot move. In conjunction with this, the parking brake (hand brake) may also be applied. On most cars, the engine cannot be started unless the lever is in this (or 'N') position.
R=REVERSE - selecting this position allows the vehicle to be driven in the reverse (backwards) direction.
N=NEUTRAL - in this position, the engine is disconnected from the drive train (gears) and the vehicle will not be propelled in either direction when the gas (accelerator) pedal is pressed. The wheels are not locked and the vehicle will be able to roll downhill if the brake pedal is not pressed.
D=DRIVE - this is the position that is typically used when the vehicle is being driven. As the vehicle increases (or decreases) in speed, the automatic gear box will select the correct gear for both speed and road conditions.
2=GEAR 2 - typically, automatic gear boxes have 3 of 4 forward gears, so some vehicles may have both 2 and 3 marked on the hear selector. By using this position, the driver 'locks' the transmission in a lower gear so that the engine will run with increased revolutions. This is useful when rapid acceleration is desired. It should be noted that maintaining high revolutions in lower gears will increase the fuel consumption of the vehicle and also the stresses on the vehicle and passengers. It should therefore be used for short periods only.
L=LOW - (may be indicated by '1') this is the lowest gear (or 1st gear) available. This position is useful when the vehicle needs to negotiate difficult terrain (such as a steep incline with a poor surface). For downward slopes, the LOW gear provides additional braking through the engine.
OD=OVERDRIVE - for vehicles fitted with this option, an extra gear is provided that has a lower ratio than the normal top gear. The power output delivered by this gear is low in comparison to the normal gears and is used for high speed cruising (on interstates / motorways etc). Engine revolutions are reduced, as are noise levels. Fuel consumption is improved.
I hope I've my explanation will be of helpful to you.
Enjoy your new ride.