Boxes like tall rectangles with two rows of two characters? If you see those, it indicates that Firefox is not able to find a font with the missing characters (which often are little image icons), or Firefox is failing to download a font that has those characters. This can occur on desktop versions of Firefox if you choose your own fonts instead of letting the page choose the fonts, or if you disable/block font downloading. However, those settings are more obscure on the mobile version of Firefox, so I'm not sure why it would be happening there.

If you meant a different kind of box, could you describe it in more detail?

i just dont understand how i will get the boxes to turn to words on my tablet so i can see the words on pearsonmymathlab. i need to know how to get the boxes to turn to words.

Could you somehow get a screenshot of the problem, or take a digital photo of it? Due to limitations on the size of files you can attach to a reply, you might host it on a picture sharing site or your webspace, if you have any.