As young people do not have experience in living independently in society and are not fully aware of social problems such as drugs and violence, they may easily fall prey to adults who would like to exploit them.

fall 在这里是动词，意思是"陷入、成为某种状态"。 prey 是名词，本义是"猎物"，引申为"被利用或伤害的对象"。 fall prey to 是一个固定短语，意思是"成为...的受害者/牺牲品"，指某人或某物被他人利用、欺骗或伤害。