help me understand what are contractors and contractor chaining please

Answer 1

Constructors are functions which are member of the classes. They are executed automatically whenever an object of the class is created.

Answer 2

Victor, do you mean constructor?
If so constructor chaining is Calling a constructor from another constructor of same class 
Here's an example :
http://beginnersbook.com/2013/12/java-constructor-chaining-with-example/