Okay, kiddo, so the national guard is a group of people who serve in the military, but they also help out their communities when there's an emergency.
So imagine if there's a big storm coming and people need help getting out of their homes or if there's a fire and the firefighters need extra hands to put it out. The national guard can come to help.
They also go through special training to be ready to help in these situations, and they are usually made up of people who live in the state or community where they serve.
But when they're not helping out in emergencies, they can also be part of the military and go to different places to help defend our country if we need it.
So basically, the national guard is like a group of superheroes who are ready to help out their communities and country whenever they are needed. Pretty cool, huh?