A layover is when you are flying on a plane to another place, but you have to stop in another city for a little while before getting back on the plane to go to your final destination. It's like taking a break or a rest stop on your trip.
Imagine if you were on a long car ride to go to your grandma's house. If you had to stop at a gas station to use the bathroom and stretch your legs before continuing on your trip, that's like a layover. You're stopping in a different place for a short amount of time before continuing on your journey.
During a layover, you might walk around the airport, get something to eat or drink, or maybe do some shopping before getting back on the plane. It's important to pay attention to the time and make sure you don't miss your next flight, but don't worry, the airline will usually give you plenty of time to get to your next gate.
So, that's what a layover is – a short stop in another city while you're on your way to your final destination. It's like taking a little break on a big trip.