It is all about understanding its structure and memorizing the new words! When you write code for the App for the first time, it's like writing a thesis with a language you are learning. It's a new challenge, a new opportunity, and in the case of software development, something so specific that it's probably never been done before.
You often get stuck, and puzzled but that's a good thing, because it could lead to the right direction. It's a signal that you have engaged in the problem solving pursuit that is math and technology and that it's time for you to dig deeper and keep going because clarity awaits.
When you are learning a new technology, whether you are learning to write your first programming language, or just the latest framework, you go through this uncomfortable phase where you know that the code you are looking at is doing this THING but you don't understand HOW exactly it's happening.
This is a normal part of the process of learning a new technology, and in fact, it's a critical part of the process.
You see when you encounter a new programming language part of your learning process includes learning to train your eye. The way to train your eye is to read a good deal of code even when you don't totally understand what it's doing.