Why has Slay Belle Katarina got an "e" on the end of "belle"

belle bel noun a beautiful girl or woman, especially the most beautiful at a particular event or in a particular group.

"the belle of the season"

Belle meaning lady (usually beautiful in an english context) or woman/female. (denotes a female)..... The "Slay belle" is a pun on the christmas phrase "Sleigh bell" (Sleigh bells ring, are you listening? in the lane, snow is glistening). Slay belle pretty much means "killing lady"

Belle means “beautiful” or “pretty” generally.