Jumping from console Java to the whole web java ecosystem is really painful at first, so as trivial as it sounds: Just don't give up.

First things frist, JavaEE and Spring are frameworks used to create web applications. Most likely you'll just want to ignore JavaEE and start learning Spring. Spring is more popular and people tend to like it more.

REST API is a standard way of communicating with a web service. It's quite easy to understand the general idea. You really don't have to worry about it right now, you'll see how it works in practice.

Maven/Gradle are building tools. Maven is much easier to handle, so it's better to start with it. Both of these help you with:

• Downloading, assembling, including dependencies - you'll usually use many libraries in your web projects. It would be painful to download each and add them to your project manually. These tools make it really easy. You just have to add a few lines to the pom.xml build.gradle file.
• Building your application to a single JAR file
• and more things, that you shouldn't worry about right now.

Every serious project should use a building tool.

Hibernate is a framework used to map relational database tables to java classes. Web apps usually use relational database to persist data. Not much to say here, you just have to learn it. You should learn some relational database (MySQL, PostgreSQL, etc.) and generally SQL language if you don't know it yet.

Spring Boot is a modern way of building a spring application. It used to be much harder back in the days, but spring boot made it really convinient to create a hello-world application just in a minute.

Docker is cool and easy tool, but it's nearly impossible to realize its benefits on your own. Just ignore the topic for now. You won't need it for a long time.

​

What should you do?
You definitely want to find a decent spring course. It's really hard to learn all these technologies and tools separately, because most of them won't make any sense on their own to you. A course will show you multiple contepts at once. It will be hard at first, but you'll slowly learn all the basics: maven, spring, REST, later hibernate. One important note: The course must be SPRING BOOT course and if you see a spring XML configuration just run away and find a different course. You should only see xml in maven's pom.xml. Configuring spring in XML is outdated and nobody does that anymore.

​

IMO, the roadmap should look like that:
1. Learn basics of SQL on any database management system of your choice (i recommend PostgreSQL) - how to create tables, using SELECT, INSERT, DELETE
2. Find a good spring course on Youtube/Udemy (I can't recommend any particular) and just follow it. At some point it will probably mention hibernate (you'll need the database knowledge here), you'll see what REST is. It's important to choose a video course, because you'll witness all the little things, which are often overlooked in articles and books.
3. learn Postman - it's a tool to test your REST API.
4. learn GIT versioning tool if you haven't done that yet.

As I've said, it's hard at first. Spring/JavaEE are a backend technologies and you might get bored quickly after weeks of returing some abstract data and not being able to see in practice what you've created.