A number less than -40 has an absolute value greater than 40.
For example a number less than -40 could be -41. -41 has a greater absolute value but is actually smaller than -40.
A person whose bank balance is less than -40 is in worse shape than the person who is -40. The person at -40 needs 40 dollars to bring their account to 0. The person at -41 needs 41 dollars to bring their account to 0. They have a greater debt.