You can use the “title attribute” for label tag.
<label title="Hello This Will Have Some Value">Hello...</label>
If you need more control over the looks,
1 . try http://getbootstrap.com/javascript/#tooltips as shown below. But you will need to include bootstrap.
<button type="button" class="btn btn-default" data-toggle="tooltip" data-placement="left" title="Hello This Will Have Some Value">Hello...</button>
2 . try https://jqueryui.com/tooltip/. But you will need to include jQueryUI.
<script type="text/javascript">
$(document).ready(function(){
$(this).tooltip();
});
</script>