What does Genesis 36:39 mean?

After Baal-Hanan died, Hadar became king. His city was called Pau, and his wife was Mehetabel, daughter of Matred, who was the daughter of Me-Zahab. Genesis 36:39 - Modern Text Bible

(This verse gives a little more detail about Hadar, including his city and family, which was unusual in this list and may hint at his importance.)