kind of like asking how a helmet prevents a motorcycle crash.
jesus man, it means if there is an unexpected expense you can easily weather it without a scramble or falling behind.
jesus man, i used these as two hypothetical high dollar unexpected expenses. how about this; the dog needs an emergency tonsillectomy and grandma was sternly warned about her gambling debts by her bookie's goons.
part of a well managed cash flow is having the ability to weather the unexpected hardship with minimal hardship.