How to learn the Unity API?

Question

C++ / C#

How to learn the Unity API, studied OOP c # now I can’t move further because I don’t understand the Unity User Manual on the unity off site, what should I do? If it's not difficult to advise courses, a book or something else.

Answer 1

Channels to help with Unity:
Emerald Powder
Brackeys
ITVDN
Maxter
Code Monkey
Eccentric Games
ARTALASKY CG
Books:
Alan Thorne The Art of Scripting in Unity
Alan Thorne Animation Fundamentals
Courses:

Answer 2

The unit has good documentation and a lot of courses, including Russian ones. On Udemy or Coursera.