a) Define a Cat class. A Cat has name. Define two constructors, one with no argument and another with the name as its argument. Initialize the name to a default value Unknown for the zero-argument constructor.

b) Create a main class. In main class, create two objects as an instance from the Cat class. The first object will call the first constructor (constructor without argument) and the second object will call the second constructor (the one with name as argument).

The instructions are quite clear as to what to do. I suggest you read through your teacher's notes or instructions and give an attempt.

Programming is learned by actually writing and compiling code. Copying or reading alone will not help you solve your next problem.
You're welcome to post your code for help, whether it compiles or not.