#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

String LCD;

void setup() {
  Serial.begin(9600);
  lcd.begin(16, 2);
  Serial.println("Bitte eingeben: ");
}

void loop() {
  if (Serial.available() > 0) {
    LCD = Serial.readString();
    lcd.clear();
    lcd.print(LCD);
  }
}