求翻译：4堆放在露天的材料必须按规定堆放整齐并有标识。经常清理建筑垃圾，每周举行一次清扫和整理施工现场活动，以保持场容场貌的整洁。是什么意思？

4 material provisions must be stacked neatly stacked in open-pit and identity. Frequently clean up construction waste, held once a week cleaning and organizing the construction site activities, to keep the field capacity field appearance clean and tidy.