Lab_04 | Programming the microcontroller

I copied and pasted this code from the lab page
but I didn't understand this code very well.
I think I need to study programming arduino more..


int servoPin = 2;   
int minPulse = 500; 
int maxPulse = 2500;
int pulse = 0;      

long lastPulse = 0;  
int refreshTime = 20;

int analogValue = 0;
int analogPin = 0;  

void setup() {
pinMode(servoPin, OUTPUT);
pulse = minPulse;         
Serial.begin(9600);
}

void loop() {
analogValue = analogRead(analogPin);    
pulse = (analogValue * 19) / 10 + minPulse;  
                                     
                                  
if (millis() - lastPulse >= refreshTime) {
digitalWrite(servoPin, HIGH); 
delayMicroseconds(pulse);     
digitalWrite(servoPin, LOW);  
lastPulse = millis();         
}
}