。
She took a night course in self-defense.
Literal
She [topic-は] self-defense-art 's night-time class [object-を] took.
護身術 ('self-defense, the art of protecting one's body') uses the productive suffix ~術 ('art, technique'), as in 美術 ('fine arts'), 武術 ('martial arts'), 手術 ('surgery'). 夜間講座 ('evening course') compounds 夜間 ('nighttime') + 講座 ('course, lecture series'). 取る ('take') is the standard verb for enrolling in a class — same metaphor as English 'take a course.' The slightly elevated vocabulary (護身術, 講座) gives the sentence an adult-education catalog feel.