const char Menu[6][6][20] = {
    {"Move", "Settings", "Notable steppers"},
    {"Start", "Stop", "Back"},
    {"Stepper X", "Stepper Y", "Back"},
    {"DisStep. X", "DisStep. Y", "Back"},
    {"XDirect", "Speed", "Steps", "Back"},
    {"YDirect", "Speed", "Steps", "Back"}
};

byte menuLen (byte i){
  for (int j = 0; j < 6; j++)
  if (strlen(Menu[i][j]) == 0) return j;
}

void setup() {
  Serial.begin(9600);
  for (byte i = 0; i < 6; i++){
    byte subMenuLen = menuLen(i);
    Serial.println(String(i) + " menu len " + String(subMenuLen));
    for(byte j = 0; j<subMenuLen; j++){
      Serial.print("["+String(i)+"]"+"["+String(j)+"] = ");
      Serial.println(Menu[i][j]);
      }
  }
}

void loop() {}