Client-server application for Android: where to start?

Question

Android

Good afternoon everyone!
Recently, I had the prospect of developing, at the request of a friend, a mobile application with ads for the sale of goods, similar to the Avito application, only with some specific functions. As far as I understand, this should be a client-server application, and I have no experience in developing such applications. I've only developed a few simple local database and Google Maps applications, and I'm not familiar with client/server development at all.
In this regard, I want to ask for advice from knowledgeable people: where would you recommend starting to master this topic? Are there any "dummies" materials to help you get familiar with client/server development? I will be grateful if you recommend specific technologies that are suitable for solving my problem. There are a lot of names on hearing, all sorts of REST APIs, Retrofit, RxJava, etc., but they all tell me little, so I ask for your advice.
And further. If this is a client-server application, then it will need a server, and I also have questions about its implementation and deployment. As far as I understand, the server will need to be placed on some kind of paid hosting? Do I need to develop it myself or are there already ready-made solutions? Please shed some light on these questions as well.
Thanks in advance for your replies!

Answer 1

You can't explain it in a nutshell, because the topic is quite voluminous, but I'll try to give a tip :)
1. "all sorts of REST APIs" - this is your main tool in the client-server architecture. I recommend clarifying this concept completely, inside and out.
2. "If this is a client-server application, then it will need a server" - the server is mainly needed to process data and save / retrieve them to / from the database. Client - to present this data to the user.
3. Yes, you need to take paid hosting. Preferably VPS.
4. There are many possible solutions for server implementation. Most popular: Laravel and Node.js for example.
5. Materials for dummies: Google.com (-: At least now you understand what exactly you need to google.
Good luck!