How to understand Symfony 4?

Question

symfony

I know more or less Laravel, thanks to Laracasts, in conjunction with the documentation, it was easy.
I decided to delve into Symfony 4. I didn’t find any really suitable training materials (except off-line docks on the Internet). I tried to start studying from the documentation, I thought about writing a small blog on symfony like when but on laravel (of course there was shitty code, but I got into the basics of the framework).
What is Doctrine and how does Data Mapper work? The thing is not complicated in theory, but I look at the docks and don’t understand what is happening there .. Constantly editing some configs, connecting unknown interfaces, etc. ... Not to mention the fact that there are a lot of loosely related articles on this topic:

spoiler

https://symfony.com/doc/current/security/entity_pr...
https://symfony.com/doc/current/doctrine/registrat...
https://symfony.com/doc/current/security/ guard_aut...
https://symfony.com/doc/current/components/securit...

Can anyone advise where to start learning the framework, or more understandable materials (available in English)?

Answer 1

Start with a demo application. There are very detailed comments to the source code.
https://github.com/symfony/demo

Answer 2

For example , https://daniil-solovyev.github.io .
Also in Russian