A stay-at-home order is like when your parents tell you that you have to stay inside for a little while and can't go out to play with your friends. Instead of your parents telling you, the government is telling everyone in a big area like a city, state or country to stay inside because there is something bad happening that we can't see called a "virus".
This "virus" can make people very sick and sometimes they have to go to the hospital. Because we don't have a cure for this "virus" yet, we have to try our best to stop it from spreading to other people.
So, when the government says to stay-at-home, it means that we have to try our best to stay inside our houses, and only go outside for important reasons like going to the doctor, getting groceries or going to work, but only if your job is very important to help people during this time.
It might feel strange or boring to stay inside, but it's important to keep ourselves and others healthy and safe until the "virus" goes away.