Magnification is simply the number of times an image's size is enlarged where size is measured in the degrees of an angle formed by lines running from either end of the image to the vertex at the observer's eye - link to illustration. In practice this simply means that if we view a 1cm line at 2x it appears to us as a 2cm line.
Resolution is a measurement of how well the smallest details of an image can be discerned. Magnification beyond the resolving power of an optical system is empty magnification. This is often encountered with extremely cheap microscopes like those bought at a toy store. On the other hand a certain level of magnification is necessary to see the details resolvable in a given image.
Our microscopes are designed so that the total magnification resulting for any choice of objective, perfectly matches the resolving power of the optical system.