A condenser serves to ensure a uniform homogeneous illumination of the object. The Abbe condenser consists of a lens system and an adjustable diaphragm. With it, you can set the optimal contrast for the object.
This refers to the magnification factor of a single microscope lens. A lens with the number 40 is referred to as a scale of 1:40 or simply a factor of 40 times. If you multiply the lens factor by the eyepiece factor, you get the magnification.