Complex sentence: The Arena Active Protection System (APS) is an active countermeasure system developed at Russia's Kolomna-based Engineering Design Bureau developed to protect armoured fighting vehicles from light anti-tank weapons, ATGMs, and missiles with top attack warheads.
Split into simpler sentences: The Arena Active Protection System (APS) is an active countermeasure system developed at Russia's Kolomna-based Engineering Design Bureau. It was developed to protect armoured fighting vehicles from light anti-tank weapons, ATGMs, and missiles with top attack warheads.