整整齐齐 is the AABB reduplicated form of 整齐 (neat/tidy). This pattern intensifies the meaning and adds a vivid, descriptive quality — it describes something being very neatly arranged, often with a sense of satisfaction or careful organization. You can use it as a predicate (东西放得整整齐齐) or as an adverbial modifier (整整齐齐地摆放). It's a fixed four-character expression, not a freely productive pattern.