Do you remember when your teacher gave you homework and asked you to show your work? She did that to make sure you solved the problem correctly and that you did it all by yourself.
Well, the Government Accountability Office, or GAO for short, is kind of like a teacher for the government. It makes sure the government is solving problems correctly and that it's doing things the right way.
The GAO is a group of people who work for the government and their job is to check and see if federal agencies (like the ones that help with schools, roads, and hospitals) are using tax money the way they're supposed to.
They check things like whether the government is doing a good job managing money, how it's using taxpayer money to improve healthcare and education, and whether it's being fair to different groups of people.
So, just like your teacher checks your homework to make sure you're doing it right, the GAO checks the government's work to make sure it's doing the right thing for all of us.