It's not really anything fancy. It's just a listing of all the actions you've made in a session. I guess so if you need to go back many, many steps, you can use Undo History to find it, instead of going back one click at a time.
I hesitate to elaborate, not knowing your specific quesion.
Beginners' Questions "Undo History", how to use
Inkscape.org
Undo History: Nothing I can find online, and I find very little, works for me, or I'm missing something in the how-to. Inkscape 92.4 newbie
Thank you for any help, Lisa1
Welcome to the forum!
I'm not sure what your question is. I agree, I don't think I've seen anything online about Inkscape's Undo History. Probably you can only find it in the manual. http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Undo.html
It's not really anything fancy. It's just a listing of all the actions you've made in a session. I guess so if you need to go back many, many steps, you can use Undo History to find it, instead of going back one click at a time.
I hesitate to elaborate, not knowing your specific quesion.