Car Stalls Every Now And Then When At Light For Awhile

What is your question?

My car stalls every now and then with only the engine shutting off but all electrical such as radio,a/c,etc still running. It blinks the oil light before cutting off and will immediately crank back up after I put it in neutral or park. Since the oil light blinks before stalling I went ahead and changed the oil. I kno it also needs a new battery, I was going get one today when this problem occurred again. WHAT COULD BE THE PROBLEM??? PLEASE HELP I'M 16 AND DON'T KNOW MUCH ABOUT CARS.