void setup() {
Serial.begin(115200);
if(!Serial) Serial.println("serial is not ok");
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
}

void loop() {
digitalWrite(3, HIGH);
Serial.println("GREEN is on");
delay(4000);
digitalWrite(3, LOW);
Serial.println("GREEN is off");
//
digitalWrite(4, HIGH);
Serial.println("YELLOW is on");
delay(2000);
digitalWrite(4, LOW);
Serial.println("YELLOW is off");
//
digitalWrite(5, HIGH);
Serial.println("RED is on");
delay(3000);
digitalWrite(5, LOW);
Serial.println("RED is off");
//
digitalWrite(4, LOW);
Serial.println("YELLOW is off");

}