यस्य of whom, धर्मज्ञः knower of righteousness, धर्मवत्सलः one who is devoted to duty, ईदृशः endowed with such qualties, त्वम् you, पुत्रः as son, सः such, महाबाहुः mightyarmed man, तव your, पिता father, दशरथः Dasaratha, अमृतः is not dead.

With you as his son, endowed with qualities of righteousness and devotion to duty, your mightyarmed father Dasaratha is not dead. (He lives through you).