Complex sentence: While Mandodari is engrossed in worshipping goddess Parvati for Ravana's well-being during the time, Hanuman disguised as a Brahmin comes to the place and after winning her confidence, tricks her into revealing the secret location of the arrow.
Split into simpler sentences: While Mandodari is engrossed in worshipping the goddess Parvati for Ravana's wellbeing, Hanuman comes to her disguised as a Brahmin. After winning her confidence, her tricks her into revealing the secret location of the arrow.