What Does Creating ArrayList Object In A Constructor Mean

import java.util.ArrayList;
public class LectureRoom{
private String courseName;
private String roomNumber;
private String Lecturer;
private ArrayList <Student> studentList;

[Code] .....

Question:

Given the following BlueJ class diagram

Lecturer class (same with previous lab, no changes needed)
Student class (same with previous lab, no changes needed)

LectureRoom (changes occurs here)

1. LectureRoom has roomNumber (e.g. A301), courseName (e.g. Java), lecturer (a reference to a Lecturer object), and studentList (a reference to an ArrayList that stores Student object).
2. LectureRoom has a constructor that receives courseName, roomNumber, and Lecturer. The constructor then sets/assign the courseName, roomNumber and Lecturer. This constructor also creates the studentList arraylist object.