program of a barometer 2014-03-29

sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;

unsigned long valeur,val;
unsigned char d1, d2, d3, d4,*text;
char i ;
void main() {

ADCON0=0x48;
ADCON1=0x80;
TRISA=0xff;
trisd=0xff;
Lcd_init();
Lcd_Cmd(_Lcd_CURSOR_OFF);



for(; {

text = ("pression");
Lcd_Out(1, 1, text);
val=Adc_Read(1);

text = ("pression");
Lcd_Out(1, 1, text);
val=Adc_Read(1);
val=val*5000/1023;
d1= val/1000;
d2=( val%1000)/100;
d3=(( val%1000)%100)/10;
d4=(( val%1000)%100)%10;
PORTD.B1=1;
lcd_chr(2,8,d1+48);
lcd_chr_cp(d2+48);
lcd_chr_cp('.');
lcd_chr_cp(d3+48);
lcd_chr_cp(d4+48);
lcd_out_cp(" Pa");
Lcd_Cmd(_Lcd_CURSOR_OFF);

}}
Please I need to understand what makes this program
Thanks