potential activity is the maximum activity you can get just by reaching the post count required , max activity you can get is equals to your current post count so for example you have 1000 potential activity and you only have 50 posts it would show you only have 50 activity but if you can make 950 more post and you will reach your 1000 activity potential without waiting for next activity periods
Great it is an nice explanation Hope will get more activity count and further i will start posting .