तदा: then, अक्लिष्टकिर्मणा: of unwearied action, रामेण: by Rama, एवम् in that way, उक्तम् having said, रक्षः Rakshasa (Vibheeshana), रावणस्य: Ravana's, सर्वम् all, बलम् strength, आख्यातुम् to speak out, उपचक्रमे: proceeded.

Then the Rakshasa (Vibheeshana) having heard that Rama of unwearied action would save him proceeded to speak out about the strength of Ravana.