An aircraft lavatory is a special place on an airplane where people can go to use the restroom. It's kind of like a bathroom, but it's on an airplane instead of in a house. The lavatory is usually located at the back of the plane, and there may be multiple ones on larger planes.
When you go into the lavatory, you will see a toilet, a sink, and sometimes a mirror. The toilet looks like a regular toilet, but it's a little different because it has to fit in a smaller space. You use it just like a regular toilet, but instead of flushing with a handle, you press a button. The sink is usually very small and has a special faucet that you have to turn on with a button.
It's important to always be careful when using the lavatory on an airplane. You need to make sure that you don't cause any messes or damage anything. It's also important to wash your hands after using the lavatory to make sure you don't spread germs.
Overall, the aircraft lavatory is a special place on an airplane where people can go to use the restroom. It's important to be respectful and careful when using it!