In this image, what is Shri hanuman siting on?
The above image is not of Hanumanji but of Angada, the son of Vali and has been taken from Episode 57 of Ramanand Sagar’s Ramayan TV series and the incident has been sourced from the Śrīrāma Pāñcālī by Krittbas Ojha (Bengali Ramayana).
Shri Rama sends Angada as an ambassador for peace to Ravana’s court just before the war. Angada sees Ravana sitting on a throne (at a height) which is when Angada rolls his tail as per the image to create a seat for himself. The incident is described in Krittibas’ Ramayana as:
बसेछे राबण राजा उच्च सिंहासने। ताहा देखि अंगदेर बड़ दुःख मने। कुण्डली करिया लेज बसिल सभाते। पुरन्दर बार येन दिल ऐराबते।
The King Ravana was sitting on a high throne. Seeing him Angada felt upset in his mind. Angada coiled his tail and sat on it as if Indra was sitting on Airavata in his court.
-(Extract of Verse 53 of Lanka Kanda)