Complex sentence: Android "L" also contains major new platform features for developers; over 5,000 new APIs were added for use by apps, and the Dalvik virtual machine was officially replaced by Android Runtime (ART), a new environment introduced as a technology preview in KitKat.
Split into simpler sentences: Android "L" also contains major new platform features for developers, with over 5,000 new APIs added for use by apps. Additionally, the Dalvik virtual machine was officially replaced by Android Runtime (ART), a new environment introduced as a technology preview in KitKat.