First arrange some people to clean the cars on stage. Then it will be ready for others to rehearsal there.

The word "清理" in Chinese can be translated to "clean up" or "remove". For example "清理垃圾“ = Clean up the trash / to remove the trash from this area. So, the translation of "先安排人员清理舞台上车辆( , ) 以备演绎人员彩排" should be " Arrange staff to remove those vehicles from the stage first, so that it's ready for the performers to do the rehearsal. Sentence analysis. 先 First 安排 arrange 人员 staff ( short form of 工作人员） 清理 cleanup / to remove 舞台上 on the stage 车辆 vehicle 以备 so that .. to be prepared for / ready for 演绎人员 performer( s ) 彩排rehearsal ( can be verb or noun )