String sentence;  // define a string variable
#define led 13  //define led pin


void setup() {
  
Serial.begin(9600); // begin serial
pinMode(led, OUTPUT); // set led pin as output pin

}

void loop() {
  
    if(Serial.available()){  //When any thing reach on serial pins 
      
  sentence=Serial.readStringUntil('\n'); //read the reached string until new line
  Serial.println(sentence); // prints the string that you read
  digitalWrite(led,HIGH); //turn led on
  delay(1000); //wait for 1 second 
  
    }
}