The phrase “keep it low key” generally means to keep something discreet, understated, or not draw too much attention to it. It suggests maintaining a level of privacy or subtlety in a situation, event, or conversation. For example, if someone says they want to keep a celebration low key, they might prefer a small gathering with close friends rather than a large, extravagant party. Overall, it conveys the idea of being relaxed and not overly flashy or ostentatious.