In plain words
Then Dhananjaya, filled with wonder, his hair standing on end, bowed his head to the Lord and, palms joined, spoke.
Word for word
Then he, Dhanañjaya, filled with wonder, his hair standing on end, bowing with his head to the God, with joined palms, spoke.
The commentators
Bhagavadgītābhāṣyam· bhāṣya
ततः तं दृष्ट्वा सः विस्मयेन आविष्टः विस्मयाविष्टः हृष्टानि रोमाणि यस्य सः अयं हृष्टरोमा च अभवत् धनञ्जयः । प्रणम्य प्रकर्षेण नमनं कृत्वा प्रह्वीभूतः सन् शिरसा देवं विश्वरूपधरं कृताञ्जलिः नमस्कारार्थं सम्पुटीकृतहस्तः सन् अभाषत उक्तवान् ॥ १४ ॥
In plain words
Seeing that form, Arjuna was swept away by sheer astonishment — every hair on his body stood on end. This is what became of Dhanañjaya. He bowed low, his head touching down in deep reverence, palms pressed together before the god who bore the universal form, and only then, hands still folded in homage, did he finally speak.
Close to the Sanskrit
Then, having seen that form, he, overcome by astonishment, whose body-hairs stood on end — this one, Dhanañjaya, became so. Having bowed, having made obeisance intensely, having become bent low, with his head, to the god bearing the universal form, with joined palms, for the sake of salutation, with hands cupped together, he spoke, said.