At attention

Okay kiddo, when someone says "at attention", it's like they're telling you to stand up straight and tall like a soldier. You have to keep your feet together and your arms down by your sides, without moving or fidgeting. This is what soldiers do when they're standing still and paying attention to their officers. It's important to be at attention because it shows respect and discipline, and it helps you focus on what you're supposed to be doing. So, if you ever hear someone say "at attention", just stand up straight and still like a soldier, and you'll be doing it right!