An airline is a company that operates planes which can take people, goods or cargo to different places around the world. Imagine a big bird that can take you on a journey high up in the sky without the need to drive on the ground. People use airlines to travel to different places, for work or vacation.
You can book your flight online or at an airline counter at an airport. To fly, you need a ticket and a passport (if you are traveling internationally) and you will have to pass through security checkpoint and immigration. Once you have checked-in, your bags will go through scanning and then will be put on the plane.
Once you are on the plane, a pilot is responsible for flying it to your destination. Cabin crew are people who are there to help make sure you are comfortable and safe during the flight. Flight attendants will serve you food and drinks, and show you where the bathrooms are.
When you reach your destination, you will collect your bags and go through another immigration checkpoint. Then you can go explore the new place you have arrived at, or go to your hotel to rest until your next adventure!