What does the following Java code demonstrate?

import java.util.ArrayList;
import java.util.List;
public class Main {
    public static void main(String[] args) {
        List<String> programmingLanguages = new ArrayList<>();
        programmingLanguages.add("Java");
        programmingLanguages.add("Python");
        programmingLanguages.add("C++");
        programmingLanguages.set(1, "JavaScript");
        System.out.println(programmingLanguages.get(1));
    }
}