I've never actually used this function in listings, though in other word processing software, "tables" and "forms" often go hand in hand. You can use a "form" to achieve things like choice selection, opinion polls, etc. I don't think there would be anyway this function could actually translate over to eBay, though I could be wrong.
If you look at my listings, you will notice that I do actually have a "table" inserted into my listing form, which I use for my store branding, and which links to my other listings. It functions as a divider between the listing details, and my normal seller details. (the fine print)
This can assist you in accomplishing formatting in your listings. Say for instance you wanted to have two different columns of text. You would first "insert" the table, and then you are given the option of how many rows and columns it should have.