It is a clever way of playing on two different meanings of the word "count." The second meaning is closely related to the word "account." An account measures how much money has been credited to you, perhaps in a bank. To "make a day count" means not to waste it, but to use it in some way that matters and is worthwhile, that adds to some imaginary total of useful things you are doing. For example, if I have a goal of learning Spanish and instead of doing nothing all day I spend a couple of hours studying Spanish, my day is not wasted. My total number of study hours has been added to. I've added to my imaginary "account." I've made the day count toward my goal of learning Spanish. "To count the days" means to do nothing but look ahead and wait. For example, "I'm counting the days until my vacation" means "I'm not really spending much time or energy on anything, I'm just waiting until my vacation begins." A lot of motivational proverbs use this kind of play on words. One that I like is "Yesterday is history, tomorrow is a mystery, but today is a gift--that's why it's called 'the present.'" Here, the word "present" is used in two different meanings: it can simply mean now, today, this instant, or it can mean a gift. The proverb means to experience joy in today and think of it as a wonderful present that has been given to you.

Make it count - let's make something good of it. Not just count your days passing by, but consider your days for making something good during each of them.