Context: LaTeX is a typesetting system. When compiling a document, a lot of really in-depth debugging information is printed, which can be borderline incomprehensible to anyone but LaTeX experts. It can also be a visual hindrance when looking for important information like errors.
If you work with LaTeX for five years and still have no idea what a hbox is or what that message means, you should not consider naming this “experience”.
Ok, go on then, tell the class what underfull hbox is. And no googling!
I already explained this in my post of yesterday in this thread. I’ve been the TeX admin at our university in my student times. I’ve been creating styles and \shipout macros. I know this stuff inside out. Heck, I’ve even read good parts of the source to understand some finer points.