Need guidance on how i can learn springboot in an efficient manner!!

Currently i started learning Java SpringBoot and i think i am stuck in the tutorial hell.
I got the course of faisal memon on Spring. But i think i am just copy pasting the things and not learning anything useful.

And also stuck in the OOPS concepts.

Can anyone specify the prerequisite for Spring and what will be the best way for me to learn it.

And in how much time i will be able to learn it.