Charbonah is the person who reminded Ahashverosh about the tree that Haman made to hang Mordechai on.
I realize that the names of most of the people mentioned in the Megillah are Persian. However, some of the names seem similar to Hebrew words, and IIRC, Rash"i explains the name "Memuchan". Is the name "Charbonah" related to the word "churban" meaning "destruction"? Does anyone explain the reason for his name?