The Code tab shows the real files behind your app. You own this code and can keep changing it.
Your app is not a black box. Behind the screens is real code, and you own it. The Code tab lets you open the files, read them, and understand how a screen or feature is put together.
Most of the time you will change your app by asking in plain words and letting the Studio edit the code for you. The Code tab is there when you want to look under the hood or make a precise change.
Your code stays yours: The project is portable. You are not locked in, and you can keep improving the app for as long as your business needs it.