What does Genesis 34:25 mean?

Three days later, when the men were still in pain, two of Jacob's sons—Simeon and Levi, Dinah's brothers—took their swords, went into the city without warning, and killed every male. Genesis 34:25 - Modern Text Bible

(While the men are vulnerable from the circumcision, Simeon and Levi take revenge, killing all the men in the town.)