I’m trying to practice how to make a rpg, but I have run into a problem where I can’t transfer my skill to another widget. I did follow this tutorial Unreal Engine Magic System RPG Series #33 - Adding Spells to Spell Book #ue4 #ue5 #unrealengine - YouTube, but it falls flat when nothing happens.
ok…
first of all:
What exactly is your problem meaning? 
If i understand you right… i hope so… you want to have a skillbook… and put a skill into it, out if a DataTable… and now want to put it into a f.e. Hotbar slot…?
Correct me if i’m wrong.
If that’s the case, you need to learn about DragAndDrop, DragAndDropOperations, Arrays, Lists and Widget Object Using (like a common Slot Widget to Drag and drop from and to another widget)
we can assist there if you want…
or… if you are willing to get your head into that Proboem:
A Skillbook/-Tree/-System is nothing more than an Inventory. It’s the same mechanic, just with a different meaning. So every Inventory system with DragAndDrop Functionality, is working 1:1 for such a thing, too.
Since i’m mid in the making of a rpg, too… i’ve done all of that during the past 3 Months 
Inventory… Skillbook… Shop… Equipment… everything the same 