C simple understanding - overloaded operator

What are overloaded operators ： utilize The existing Some kind of operator , in the light of Custom class or structure , Define an operation .
 1, Instead of creating new operators ,
 2, Custom classes or custom structures

Grammatical details ：
public static Dogoperator +(Dog male,Dog female){ // The return value is Dog   operator + Is an overloaded addition operator
    ……
    return new Dog();
}

Which operators can be overloaded ：
1, Unary and binary operators can be overloaded
2, Be careful ： If it is a unary operator , The operand must be a class or structure     If it is a binary operator , At least one of the two operands is a class or structure

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Pet[] pet = new Pet[] { new Cat("Cathy"), new Dog("Jack"), new Dog("Merry") };
            for (int i = 0; i < pet.Length; i++)
            {
                pet[i]++; // The program runs here , The following... Will be called automatically ++ Overloading methods 
                pet[i].ShowAge();
            }
        }
    }

    class Pet {
        private string name;
        private int age;

        public string Name { get => name; set => name = value; }
        public int Age { get => age; set => age = value; }

        public Pet(string name)
        {
            this.Name = name;
        }

        public static Pet operator ++(Pet pet) {//public static Is a must , return Pet type , Adopt self increasing heavy load 
            ++pet.age;
            return pet;
        }

        public void ShowAge()
        {
            Console.WriteLine(name+" In the age of ："+age);
        }
    }

    class Dog : Pet {
        public Dog(string name):base(name) { }
    }
    
    class Cat : Pet { 
        public Cat(string name) : base(name) { }
    }    
}