My First Item QuizHub got rejected for not meeting coding standard. Need some clarifications and help.

Hi Everyone,
I need your help.
My first item QuizHub ( web app to create quizzes built with reactjs and firebase ) got rejected for not meeting coding standard.
I am ready to work harder and improve it.
One thing comes to my mind is ‘Not adequate comments’.
Apart from that What am i suppose to improve?
And it is mentioned that I cannot resubmit the item again.
Does it mean even after improving my code and adding some new features, I should not submit it again?
Live Demo of my app - QuizHub
Thanks for your time and valuable suggesstions in advance.