Okay, imagine you have a big number, like 1000. Now, let's say you want to make it smaller by taking away some of it. You could take away 100, or even 500, and it would still be a big number.
Now, imagine you have a special type of number that you can't take away from without it getting *really* small. This special type of number is called a "howler".
Think of a howler like a super fragile toy. If you try to take it apart or mess with it too much, it will break into tiny pieces and become practically useless.
So basically, a howler is a kind of number that you can't mess with too much or it will become too small to be useful.