A cool-off period is the time, during which, you're not allowed to take out another cash advance. Why all the rules? Well, it’s there to help you improve your money habits so that you don’t become forever reliant on emergency funds (don’t say we don’t have your back).
Cleo’s cool-off period lasts a full 24 hours from when you took out your advance. So, if you took out your advance at 10 am on Monday, you'll be, in theory allowed to take out one out on Tuesday at 10 am.
However, there is a catch: you'll need to have also repaid it. You cannot have an active advance and request another. Patience is a virtue after all, and Cleo just happens to enforce it.