Magnification is the number of times the size of an image is increased. So for instance 1/10,000 means that it's been increased in size 10,000 times.
Resolution or resolving power as it's also called is the ability to discriminate between two seperate points within your image. So for instance if you zoom something a million times, it might be zoomed in a million times upon, but you won't be able to make anything of it because the resolution is so poor. In short the resolving power of a microscope it's ability to show two objects as separate. A good piece of information to remember is that the maximum resolution of a light microscope is limited by the wavelength of light which is about 0.2µm.