i wanna understand how TIMER2 work ??

Projects Programming
1

please can someone explain to me this lines , specialy lines 3,4,5,6 =( =(

TIMER_CONFIG_KHZ(val) ({
const uint16_t pwmval = SYSCLOCK / 2000 / (val);
TCCR1A = _BV(WGM11);
TCCR1B = _BV(WGM13) | _BV(CS10);
ICR1 = pwmval;
OCR1A = pwmval / 3;
})

2

Full description in the data sheet of AtMegaxxxx

3

For beginners: http://letsmakerobots.com/content/arduino-101-timers-and-interrupts