Getting up to speed on the Admin UI can be a little daunting because of the number of different technologies involved. The trick then is to use the list below as a guide, and select the tutorials you need to fill in the gaps in your knowledge. And yes the code will make sense eventually.
React provides a component based framework for the user-interface.
React-Router controls the navigation between (virtual) pages in the application.
React-Redux provides a method for tracking the state of the user interface across components.
Immer provides support for immutable data structures. While not exactly a “core technology”, it’s included here as it’s used to manage Redux state.
Node Package Manager (npm) is the world’s largest software registry. We use it to pull in the software packages we need to build and run our code. You will need to have a general idea of how npm and package.json work.
If you want to understand how Immer works with Redux read Introduction to Immer.
The NPM home page is a good spot to find NPM Documentation. There are also dozens of tutorials available.
Material UI is a popular React User Interface framework, that provides a set of layout components, navigation components, and form controls for building web pages. It also controls how color themes are handled in the Admin UI.
Formik has a set of helper functions that make it easier to deal with Forms.
Yup provides a framework for doing Form validation.
For Material UI, I would start by looking through the documentation on the Material UI Home Page. Once you have the basics, head to youtube and watch one of the Tutorials.
You can find information on Formik at the Formik Home Page, and Yup at An Introduction to Validation. There is also a tutorial showing the interaction between the two packages at the React Native School.
There is a good overview of Axios in its NPM Package Doc. There are also several tutorials on it, ranging from the 10 minute overview to the 40 minute in depth discussion.