two sticks of memory. I saw this exact question a couple months back. The A10 relies so much on memory bandwidth that having 2 sticks of fast ram (1866 Mhz+) is needed for gaming.
Having two sticks means you can run it in dual channel mode which doubles the memory bandwidth. Since the RAM functions also as the VRam as well as the RAM, it's very important to have it running fast, otherwise the GPU will be severely bottlenecked.
EDIT: Here are some benchmarks: http://forum.notebookreview.com/gaming-software-graphics-cards/641254-amd-llano-6620g-benchmarked-various-ram-configurations.html
Your system is currently like the green bars.
Another interesting article: http://hexus.net/tech/reviews/cpu/46073-amd-a10-5800k-trinity-needs-faster-ram/