A serial comma is called that because it is used to separate several items (three or more).
By the way, this book cover is here because I'd like to recommend it. By a local author, I Am Not a Serial Killer is about a boy whose mother runs a mortuary. Here is part of the book description from Amazon.com:
"John Wayne Cleaver is dangerous, and he knows it. He’s spent his life doing his best not to live up to his potential. He’s obsessed with serial killers, but really doesn’t want to become one."
But, back to commas. . . .
