打分 is a separable verb (离合词) meaning 'to grade' or 'to score'. The two characters 打 and 分 can split apart when you add a measure word, number, or descriptive word in between — for example, 打高分 (give high marks) or 打了八分 (gave eight points). The person or thing being graded is typically introduced with 给 (gěi): 给试卷打分 (grade the papers). In a separated form, the object or adverbial goes between 打 and 分.