What does EnumSet really mean?

I have the following example:

import java.util.EnumSet;import java.util.Iterator;public class SizeSet {    public static void main(String[] args) {        EnumSet largeSize = EnumSet.of(Size.XL,Size.XXL,Size.XXXL);        for(Iterator it = largeSize.iterator();it.hasNext();){            Size size = (Size)it.next();            System.out.println(size);        }    }}enum Size {  S, M, L, XL, XXL, XXXL;}

In this code I can understand that the Enum creates an Enum type of Sizes.

My question is: is largeSize an object of EnumSet type? What does it really mean? I really want to understand it better.