If a number is closer to the start of the number line than another, it will be less than the number you're comparing it to. So < pointing to the start of the number line means less than.

Let’s count them. Harry has 3 apples left. So, one less than 4 is 3. One more than 6 is 7. You can also use a number line to show this. On a number line you can see that 1 more than 6 is 7.