Well, a guidance system is like the GPS in our cars. You know when mommy and daddy put in an address and the GPS tells them the directions to get there? That's a guidance system!
Guidance systems are used in a lot of things, like airplanes, missiles, and even boats. They are made up of sensors and computers that work together to figure out where exactly you are and help you get to where you want to go.
Just like how the GPS in our car tells mommy and daddy when to turn left and how far they need to go before the next turn, a guidance system in an airplane tells the pilots where to fly and when to make turns.
So basically, a guidance system is a really smart computer that helps us get to where we want to go by telling us the best way to get there.