This is the current Batgirl, Cassandra Cain. She was raised the daughter of Cain, an extremely successful mercenary/assassin, who trained his daughter in the tools of his trade. He neglected studies that didn't directly impact her fighting capabilities, so things like social skills and language were ignored. Until she made the choice to not kill people and trained under Batman's wing, she could barely speak. In fact, her native language was violence; she would say 'Hello' by cold-cocking people. Under Batman and Oracle, the original Batgirl, she's matured somewhat.