How can I understand classes?

Answer 1

Classes are the blueprint of the program (like a blueprint of building which tells the workers where to make what) where you make functions of the program. Then using this functions you make a whole building or program using this blueprint. Hope you understand.

Answer 2

By trying it in the playground and manipulate it whatever you could think about :)

Answer 3

Quite simply a class is just a place where you put similar functions.
The variables and definitions of the functions are all contained within the class.