|Surpanaka, sister of Ravana appears in the forest during the Vanavasa and pesters Lakshmana to marry her as she is beautiful.
Rama and Seeta make fun of Lakshmana as well, and they all get to know that Surpanaka is in the disguise of a beautiful women and Rama orders Lakshmana to disfigure her by damaging her nose for the trouble she has created.
So Lakshmana cuts the front part of her nose and this leads to the beginning of abduction of Seeta by Ravana.
In the above scene, you can see Rama and Seeta enjoying under the tree and probably Rama is trying to pluck some fruits for Seeta and she is standing in a tribhangi posture.
Lakshmana with great might is cutting the front part of the nose of Surpanaka. I am not sure about the image below Lakshmana's leg.