If Anna is the lead unit in a battle in which she kills the enemy, she has a chance of obtaining Gold based on her Luck stat as the activation percentage.
Ikkaku Senkin is a Japanese phrase that roughly means "one grab, a thousand gold", meaning obtaining money through little effort. It is also one of Anna's Japanese cut-in quotes in both Awakening and Fates.
Make a Killing is an english idiom used to describe making a lot of money very easily. It is also a pun on the fact that Anna needs to kill an enemy for the skill to activate.