Heads up is an informal expression used to warn someone about something that is going to happen.
Common usage examples:
1. "Heads up! The boss is coming!"
2. "Just giving you a heads up that the meeting has been moved to 3pm."
3. "Thanks for the heads up about the traffic jam."
4. "I wanted to give you a heads up that your package will arrive tomorrow."
Heads up这词儿啊，就是提醒别人注意点儿啥事儿要发生了，相当于咱们说的"注意啦"、"提个醒儿"。
常见用法给您举几个例子：
1. "小心！老板来啦！"（原意：Heads up! The boss is coming!）
2. "跟您打个招呼啊，会议改到下午3点了。"（原意：Just giving you a heads up that the meeting has been moved to 3pm.）
3. "多谢提前知会堵车的事儿。"（原意：Thanks for the heads up about the traffic jam.）
4. "我这是给您提个醒儿，您快递明天就到。"（原意：I wanted to give you a heads up that your package will arrive tomorrow.）
文化背景补充：这词儿最早是体育用语，提醒运动员"抬头看球"，后来演变成日常提醒用语。现在年轻人聊天经常用"提个醒"、"知会一声"来翻译，特别接地气儿！