A lot of the blueprint documentation is kind of handholdy, and assumes no prior experience.
The C++ documentation is written with the expectation of prior experience with C++ in mind.
In many cases, knowing how something works in blueprints will make it rather self-explanatory how something works in C++.
If you are not experienced with C++ and want to get started deeper into it, right now, in my experience, the gap is best filled with third-party paid C++ courses. Pattuzzi (Gamedev.tv) / Tom Looman are the people you might want to look up. I’m not affiliated with either. The courses won’t break the bank at sale prices.