const int green = 27;
const int yellow = 14;
const int red = 12;

/* */
void setup() {
  //Note If you want code to run once put it in the setup
  Serial.begin(9600);
  pinMode(green,OUTPUT);
  pinMode(yellow,OUTPUT);
  pinMode(red,OUTPUT);

  //If you want the green light to switch on and run once 
  /* 
    digitalWrite(green, HIGH);
    delay(1000)
    Serial.println("Green Light ")
   */
}

void loop() {
  // put your main code here, to run repeatedly:
  //Green Light
  digitalWrite(green,HIGH);
  Serial.println("Green Light");
  delay(1500);
  digitalWrite(green,LOW);
  delay(1000);

  //Yellow light
  digitalWrite(yellow,HIGH);
  Serial.println("Yellow Light");
  delay(1500);
  digitalWrite(yellow,LOW);
  delay(1000);

  //Red light
  digitalWrite(red,HIGH);
   Serial.println("Red Light");
  delay(1500);
  digitalWrite(red,LOW);
  delay(1000);
}