It means when someone is not satisfied with their own lot in life and always assumes that there are better things in other places. It expresses the idea that people often think a different set of circumstances would bring them greater joy.
This idiom encapsulates the human quality of always wanting something different than what you have. It assumes that your neighbor’s yard is greener than yours, when, in reality, they are the same.
At one level, it is an observation that there is usually a better situation than the one you exist in while at another level, it is advising you that in all life’s endeavours, there is a limited amount of information available for making choices.
So, make it a point to be a learner and seeker of knowledge throughout your life and let your inner wisdom.guide you on rhe path of success.