Complex sentence: Pro is a 2D animation software developed and sold by Celsys that's available for Microsoft Windows and Mac OS X. It handles the entire animation production from digitally drawing or tracing to exporting in Flash and QuickTime, and is popular in Japan's anime industry.
Split into simpler sentences: Pro is a 2D animation software developed and sold by Celsys. It is available for Microsoft Windows and Mac OS X. It handles the entire animation production from digitally drawing or tracing to exporting in Flash and QuickTime, and is popular in Japan's anime industry.