What about commas?

var students = [ 
  { 
    name: 'Dave',
    track: 'Front End Development',
    achievements: 158,
    points: 14730
  },
  {
    name: 'Jody',
    track: 'iOS Development with Swift',
    achievements: '175',
    points: '16375'
  },
  {
    name: 'Jordan',
    track: 'PHP Development',
    achievements: '55',
    points: '2025'
  },
  {
    name: 'John',
    track: 'Learn WordPress',
    achievements: '40',
    points: '1950'
  },
  {
    name: 'Trish',
    track: 'Rails Development',
    achievements: '5',
    points: '350'
  }
];

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

let firstArray = [];

for (let i = 0; i < students.length; i += 1)  {     
let firstVar = `<b>Name: </b>` + students[i].name +  '<br>' 
             + `<b>Track: </b>` +students[i].track + '<br>'
             + `<b>Achievements: </b>` +students[i].achievements + '<br>'
             + `<b>Points: </b>` +students[i].points + '<br><br>';
firstArray.push(firstVar);
firstArray.join(` `)
};
print(firstArray);