What does "head up" mean?
Native speaker’s answer
Rebecca
"Heads up" is a common expression that is used to warn someone of something. It is usually a warning for something immediately approaching them that could cause harm. It is similar to saying "watch out" or "look out". Ex: Heads up, the ball is about to hit you! "Heads up" can also be used to give someone information to prepare or warn them for something in the future. Ex: Just a heads up, the professor doesn't like it if you eat in class.