Overdraft

Hi sir , hopefully you are doing well . I want to get this concept of overdraft right I just don't wanna learn rules as u said it's not good. So overdraft is a negative bank balance I believe. in cash terms, When receivables are low means we have more cash, When high cash is low So does that mean fall in receivables means the cash will be more at bank and there will be less negative (bank balance) so that's how it will give us a overdraft interest saving ? Can u tell me if my concept is right