Short for, "You win some, you lose some". Usually employed when a situation or endeavour doesn't pan out in a auspicious manner in spite of a party's best efforts. Interestingly enough, despite the inclusion of the word 'win', ironically the phrase is often intended to console a loser.
"Wow, you spent $700 on that date and she went home with the waiter. Ah well bro, you win some..."