General Query

What I meant was, if one is given 10 objects to create, with different names. In that case, I think creating objects using the For loop might not work. Yes, I meant ArrayList, cause I don't know how to add objects there yet, so I was trying to add them using '+' notation, like when you add Strings together. I was given a task to print 10 cat objects, as there was nothing in it, that's why I asked about 'shouldn't there be something inside?', I thought it might show nothing. Like some previous task, there was a task to increment catCount static variable when the Class is called & print the catCount. Looks like I made you confused. LOL, Don't worry, Mr. Thomas, I'm working on my conversational skills, through lots of typing, I may not speak well if I am to meet someone face to face though..

When you add Objects to a list or an array then you do not put that entire object into the container but just the reference to that object. That reference you can that grab again from the container and assign it to a variable. That's similar to

Cat cat = new Cat();
Cat sameCat = cat;

Both reference variables are referencing now the same object. OK, you learned a little bit about lists and know now how to add objects. Cool... Cause the object does not have any state and behavior it doesn't mean it can't be printed. By default the class name followed by a hexed hash code is printed. If you need another output you need to code it. Again you learned something new. You can add elements one by one like

Cat cat1 = new Cat();
Cat cat2 = new Cat();
...
cats.add(cat1);
cats.add(cat2);

or shorter

cats.add(new Cat());
cats.add(new Cat());
...
cats.add(new Cat()); // 10th repetition

But you also can put that adding into a loop

for (int i = 0; i < 10; i++) {
    cats.add(new Cat());
}

Or you use a while loop

while (cats.size() < 10)
    cats.add(new Cat());

or you make use of the constructor... but I do not know if CG accepts that. And I don't recommend that as this is really unexpected behavior and fellow coders may hate you for that.

public Cat() {
    if (cats.size() < 10)
        new Cat();
}

public static void main(String[] args) {
    new Cat();
    printCats();
}

To that you can add your id if you want... and override the toString method so you get some meaningful output. But as said, I'd go for the while loop.

public class Cat {
    private static List<Cat> cats = new ArrayList<>();
    private final long id;
    private static long counter = 0;

    public Cat() {
        id = counter++;
        cats.add(this);
        if (cats.size() < 10)
            new Cat();
    }

    public static void main(String[] args) {
        new Cat();
        printCats();
    }

    public static void printCats() {
        cats.forEach(System.out::println);
    }

    @Override
    public String toString() {
        return "Cat{" +
                "id=" + id +
                '}';
    }
}

If you don't understand everything now, don't worry. You'll learn that soon enough and you also learned about the CG method. They teach a little bit and give you tasks. Some are really demanding and you need to read more about stuff in the internet. Even better would be to read a good Java book at the same time.