Being an “old school” programmer, I learn new languages by tearing apart code written by others to see what I can use.
Having tutorial videos is a plus.
The problem is, either way you come across nodes you don’t quite understand the purpose.
With videos (most are very good) you get " Put this node here. Then put this node here. etc… with the author assuming you know what the nodes do.

I’ve tried doing searches on some only to get results that are even more confusing or not relating.
After reading a lot of forum posts and seeing tutorials for people who are new to blueprinting I tend to believe there is a whole lot of people who are even more confused.

You would think Epic or someone would come out with a glossary of all nodes, what they do and where you would probably use them.

Epic has it’s own Blueprint’s documentations here. The usage of each node is not always in the description, but still you can get a LOT of information.

You can learn some stuff from content examples. However Epic overdid there a bit, most of those examples are all together in bigger levels, so sometimes it is hard to see what is for what.
Unreal documentation has some good text based examples, list of nodes is of that kind when somebody exports all code to wiki and does not add any more comments.

Hardest thing to learn about unreal is how the data and tasks flow and interact. Reasons for some base blueprints are unknown until you for eg start doing multiplayer.