Complex sentence: H2O is open-source software for big-data analysis, which is produced by the start-up H2O.ai (formerly 0xdata), which launched in 2011 in Mountain View, California (in Silicon Valley).
Split into simpler sentences: H2O is open-source software for big-data analysis. It is produced by the start-up H2O.ai (formerly 0xdata), which launched in 2011 in Mountain View, California (in Silicon Valley).