"Don't count your chickens before they hatch" is a saying that cautions against having unrealistic expectations or presuming success before it is assured. It reminds us that intentions and results can change suddenly, and it urges patience and prudence. 

Things in life don't always go as planned because of a variety of uncontrollable circumstances. We run the danger of disappointment or failure when we make assumptions about the future. This proverb emphasizes how crucial it is to live in the moment and make sure everything goes as planned before celebrating. 

It is applicable to a range of contexts, including both personal and professional endeavors. The lesson is straightforward;  don't make assumptions or judgments based on expected success until outcomes are assured. Remaining calm and making accurate estimates require a combination of patience, careful planning, and flexibility.