Interfacing Motion Detection sensor HC-S501 with Arduino

/* Motion Sensor Prototype Code
 * modified 23 January 2022
 * by Osama Ahmed
 */

// define pins
#define BLUE 9
#define GREEN 6
#define RED 5
int pirPin = 12;                  // PIR Out pin
int buzpin = 13;                  // Buzzer In pin
int pirValue;                     // Place to store read PIR Value
int pirStat = 0;                  // PIR status

void setup() {
  pinMode(pirPin, INPUT);         // declare sensor as input
  pinMode(buzpin, OUTPUT);        // declare Buzzer as output
  pinMode(RED, OUTPUT);           // declare RED LED as output
  pinMode(GREEN, OUTPUT);         // declare GREEN LED as output
  pinMode(BLUE, OUTPUT);          // declare BLUE LED as output
  digitalWrite(RED, HIGH);
  digitalWrite(GREEN, LOW);
  digitalWrite(BLUE, LOW);     
  
  Serial.begin(9600);
  Serial.println("Serial Monitor connected");
  delay(1000);
  Serial.print(".");
  delay(500);
  Serial.print(".");
  delay(500);
  Serial.println(".");
  delay(500);
  Serial.println("Please let your sensor calibrate");
  delay(1000);
  Serial.println("for 15 to 30 seconds before testing");
  delay(1000);
  Serial.print(".");
  delay(500);
  Serial.print(".");
  delay(500);
  Serial.println(".");
  delay(500);
}

void loop(){
 pirStat = digitalRead(pirPin); 
 if (pirStat == HIGH) {             // if motion detected
   Serial.println("Motion Detected!");
   analogWrite(BLUE, 255);
   analogWrite(RED, 255);
   analogWrite(GREEN, 255);
   digitalWrite(buzpin, HIGH);
   delay(100);                      // wait for a second
   analogWrite(BLUE, 0);
   analogWrite(RED, 0);
   analogWrite(GREEN, 0);
   digitalWrite(buzpin, LOW);
   delay(100);                      // wait for a second
 } 
 else {
   analogWrite(BLUE, 0);
   analogWrite(RED, 0);
   analogWrite(GREEN, 0);       // LED stays off if no motion detected
   Serial.println("No Motion Detected!");
 }
}