'Undefined'

var students = [
  {
    name : 'Nour El-din',
    track : 'Front-end web development',
    achievements : 5,
    points : 3000
  },
  {
    name : 'Mariam',
    track : 'IOS',
    achievements : 6,
    points : 1000
  },
  {
    name : 'Hala',
    track : 'Android',
    achievements : 8,
    points : 300
  },
  {
    name : 'Heba',
    track : 'Web Design',
    achievements : 10,
    points : 30000
  },
  {
    name : 'Ahmed',
    track : 'C#',
    achievements : 15,
    points : 5000
  }
];

var messege;

function print(message) {
  var outputDiv = document.getElementById('output');
  outputDiv.innerHTML += message;
}

for (var i = 0; i < students.length; i++) {
  for (var key in students[i]) {
    if ( students[i][key] === students[i].name ) {
      messege += '<h2>' + key + ' : ';
      messege += students[i][key] + '</h2><br>';
    } else {
        messege += key + ' : ';
        messege += students[i][key] + '<br><br>'
      }
    }
  }

print(messege);