Explain statements in the program blinking leds

Hi all

You to explain his statements in the program blinking leds

#include "lm4f120h5qr.h"

void main(void)
{
long i;
SYSCTL_RCGC2_R = SYSCTL_RCGC2_GPIOF;
GPIO_PORTF_DEN_R = 0x08+0x04+0x02;
GPIO_PORTF_DIR_R = 0x08+0x04+0x02;
while(1)
{
GPIO_PORTF_DATA_R=0x02;
for(i=0;i<3000000;i++);
GPIO_PORTF_DATA_R=0x00;
for(i=0;i<5000000;i++);
}
}

Because his new learn lm4f120 should difficult to understand, hope you to explain the above statement 

Thank :)