The example is not correct.A led needs a constant current.So you can't feed a 12V led with a 12V battery. The current will be a lot too much or a lot too less.I assume that there are specific power supplies for those 12V leds.Normally a led with a resistor is switched on and off.
Zapro, you could be wrong.Led modules often consist of a few leds parallel and serial. Sometimes 16 'leds' are used inside the module with 4 rows and 4 columns. So the result would be 4 leds of 3V is 12V.