I downloaded the pipeline and uploaded some pictures (tiff) in the program, but I am confused about the results I got in the spread sheet.
i'm confused too, which pipeline did you download? which tiff and how does it look like?
CellProfiler natively gives you object size in pixels, but does NOT give you any information on microns. It totally depends on users to convert from pixel to microns, because only user know the resolution of the microscope, i.e. how big is 1 pixel in micrometers, at what magnification etc.
So if you are using someone's pipeline, please be specific.