Hora

 function Hora() {

  var now = new Date();
  var year = now.getFullYear();
  var month = now.getMonth() + 1;
  var day = now.getUTCDate() - 1;
  var hora = now.getHours();
  var minutos = now.getMinutes();
  var dias_semana = ["sábado", "domingo", "lunes", "martes", "miercoles", "jueves", "viernes"];
  var nombreDia = (dias_semana[now.getUTCDay()]);
  //var nombreDia = now.getUTCDay();
  var string = day + "/" + month + "/" + year + "-" + hora + ":" + minutos + "\n";

  SpreadsheetApp.getUi().prompt(string);

}