अथ व्यवस्थितान् दृष्ट्वा धार्तराष्ट्रान्कपिध्वजः। प्रवृत्ते शस्त्रसंपाते धनुरुद्यम्य पाण्डवः ॥

atha vyavasthitān dṛiṣhṭvā dhārtarāṣhṭrān kapi-dhwajaḥ pravṛitte śhastra-sampāte dhanurudyamya pāṇḍavaḥ hṛiṣhīkeśhaṁ tadā vākyam idam āha mahī-pate

Then, beholding the sons of Dhritarâshtra standing arrayed, and flight of missiles about to begin, he whose crest is an ape, the son of Pându, took up his bow,

In plain words: Arjuna, whose flag shows a monkey, sees Dhritarashtra's sons lined up as the arrows are about to fly. He picks up his bow.