Large Classes are classes that span too many lines. When a class gets too long, perhaps it is responsible for more tasks than it should be, or could be further generalised and additional classes that inherit from it can implement more specific features.
class LargeClass: # Many class variables def __init__(self): # Many instance variables # Many Methods
Books about code smells
Learn to write better smelling code.
Refactoring: Improving the Design of Existing Code
Code smells: A Predictor of Remarkable Quality Improvement
Clean Code: A Handbook of Agile Software Craftsmanship