Need help understanding code (Exception Handling)

class Levels {
static public class Ex1 extends Exception {}
static public class Ex2 extends Exception {}

static public void main(String[] args)
{
    try {
        try {
            for (int i = 0; i < 3; i++) {
                System.out.println("Looping...");
                level1();
            }
        } catch (Ex1 ex) {
            throw new Exception("123");
        } catch (Ex2 ex) {
            throw new Exception("ABC");
        } catch (Exception ex) {
            throw new Exception("ABC123");
        } finally {
            System.out.println("Foo");
        }
    } catch (Exception ex) {
        System.out.println(ex.getMessage());
    } finally {
        System.out.println("Bar");
    }
}

static private void level1() throws Exception
{
    System.out.println("Entering Level 1");
    level2();
    System.out.println("Leaving Level 1");
}

static private void level2() throws Exception
{
    System.out.println("Entering Level 2");
    level3();
    System.out.println("Leaving Level 2");
}

static private void level3() throws Exception
{
    throw new Ex2();
}
}

Output -

Looping...

Entering Level 1

Entering Level 2

Foo

ABC

Bar

I'm confused after Entering Level 2. Not sure how it gets to Foo and onwards.

static private void level3() throws Exception
{
    throw new Ex2();
}

Might be cause I don't understand "throw", "throws", "extends" and "new". Can someone explain it in simplest term possible.