वीर्योत्सेकात् with pride of prowess, निरस्तस्य thrown away, तस्य दुन्दुभेः Dundubhi's, गिरिकूटोपमो as the mountain peak, महान् huge, एषः this, अस्थिनिचयः heap of bones, सम्प्रकाशते is shining

'Hurled with the pride of his(Vali's) prowess is this heap of bones of Dundubhi here, which shines like a huge mountain peak.