What is the significance of kemet?

The word "Kemet" in the context of history refers to the name for ancient Egypt given by the ancient Egyptians themselves. It is an example of an endonym, the name applied to a region by its natives. By contrast, the word "Egypt" itself is an exonym, a word created for the English language, but something that would not mean anything to an actual ancient Egyptian. In fact, the word "Egypt" developed only at the very end of thousands of years of ancient Egyptian history; the Romans applied the term "Aegyptus" for the ancient kingdom of pharaohs and pyramids.
Exonyms and endonyms can be found throughout all of history. As a modern example, "China" is an English exonym, a word based upon the historical Qin Dynasty. However, the Chinese word for their country is totally different: Zhuonghuo, which literally means "Middle Nation."
The use of endonyms and exonyms is further complicated by the fact that ancient Egyptian is a totally dead language: nobody speaks it today. This means linguists can approximate what it was meant to sound like, but we cannot be certain. Kemet was possibly pronounced differently by the ancient Egyptians themselves.