ok so as you are in class 11 only, the coaching culture can be difficult to adjust with.
also i think right now, they must be teaching physical chemistry or maybe chemical bonding.
just read ncert of whatever chapter is going on in the coaching on a day to day basis and practise more and more questions, eventually you will understand everything,
its not you are not understanding, you just know right now how to study like how many hours a day.
just keep calm, ask your doubts in fiitjee and here as well, you will definitely understand everything.