your academic standing is how you rank in your class. being in the top 10 would mean you have a good academic standing, and being in bottom 10 would mean you have a very low/bad academic standing.

Your academic standing is where you stand in relation to you degree. If you have 30 points out of 90, then you have completed already a third of your degree. This academic standing is measured when you want to change universities. If you have a Chinese degree then you have no academic standing in overseas universities. But there are exceptions: Doctors in Chinese Medicine for example. It has nothing to do with your good or bad grades. It has only to do with whether you have passed or not.

Good academic standing means that your grades aren't bad. If you are failing, or on academic probation, then you are not in good academic standing. Otherwise you are good :)