I am not understanding any of this.Should i go back to javasctipt and learn and then came again?

Answer 1

I know js but I haven't touched drag and drop api yet ,not sure why they included it in html5 , literally confusing for beginners

Answer 2

Firstly I would do a secondary read on the chapter and try the example codes. Secondly I would look into the lesson comments, people write explanations about things there sometimes, might help. Jumping to another lesson doesn't help for me (personal opinion).
For future reference, please be descriptive with the question, "I am not understanding any of this" is a broad topic (note "this" was not specified).