It means to make a lot of money from a venture.
They would make a killing. If you mean a more serious answer, they make whatever they charge.
make a killing
so mean you'll feel like killing herso mean you'll feel like killing her
If you mean "fraternicide", then it is the killing of your sibling. As opposed to patricide, which is the killing of your father, or matricide which is the killing of your mother.
killing
Killing a god.
It is the area within a slaughter house used for the killing of animals.
The cast of Make a Killing - 2010 includes: Don Scribner as The Killer
The killing of a mouse, or murine.
It means killing his or her brother
to kill something
killing mysellf laughing!