Won't start if it sits

If my car sits for a few hours it wont start. It makes a clicking sound and a couple of times It turned over when I pumped the gas hard. If I jump it it starts right up. It sounds different when its just the battery that is dead. I am going to go to the auto parts store and ask them to check my battery for me as well as plug it into the thing that gives you codes . I will be back. Thanks