Why is CopyOnWriteArrayList used in this example, and what is its primary advantage?

import java.util.concurrent.CopyOnWriteArrayList;

public class SafeIteration {
    private CopyOnWriteArrayList<Integer> list = new CopyOnWriteArrayList<>();
    
    public void addElements() {
        for(int i = 0; i < 50; i++){
            list.add(i);
        }
    }
    
    public void iterateElements() {
        for(Integer num: list) {
            System.out.println(num);
            try { Thread.sleep(10); } catch (InterruptedException e) {}
        }
    }
    
    public static void main(String[] args) throws InterruptedException {
        SafeIteration si = new SafeIteration();
        Thread t1 = new Thread(() -> si.addElements());
        Thread t2 = new Thread(() -> si.iterateElements());
        t1.start();
        t2.start();
        t1.join();
        t2.join();
    }
}