The phrase, to kill two birds with one stone, means “to accomplish two goals by one action.” For example:
I’m going to kill two birds with one stone by getting gas when I go out for groceries.
Let’s save money and become healthier by not eating beef; that way, we’ll kill two birds with one stone!
The huge popularity of this phrase probably comes from our obsession with using time well in Western culture. It is believed to originate from the Greek myth of Daedalus, who literally killed two birds with one stone in order to get feathers to make wings, so he and his father could escape a labyrinth where they were imprisoned.
This saying was first used in print by philosopher Thomas Hobbes in 1656.