You are missing a 'r' in attr and your syntax is wrong.
Try this code.
$('.bx-pager-link').on("mouseenter", function(){
$('.bx-pager-link').attr("title", "This is a title");
});
EDIT: For tooltip on pager, you need to do this,
JS:
var slider = $('.bxslider').bxSlider({
pager: true,
pagerCustom: '#bx-pager',
)};
HTML:
<div id = "bx-pager">
<li>
<a data-slide-index="0" title = "Tooltip text goes here" class = "slide" href="">
Slide1
</a>
</li>
<li>
<a data-slide-index="1" title = "Tooltip text goes here" class = "slide" href="">
Slide2
</a>
</li>
<li>
<a data-slide-index="2" title = "Tooltip text goes here" class = "slide" href="">
Slide3
</a>
</li>
<li>
<a data-slide-index="3" title = "Tooltip text goes here" class = "slide" href="">
Slide4
</a>
</li>
</div>
PS: Don't forget to write "data-slide-index" in . More