In plain words
One day he came near her and went on describing his power, his abilities and his splendours in many ways. "I am a man of great learning; I have studied the sixty-four arts; I have even studied the arts of Gajakarṇa and Gokarṇa, which are found nowhere else in the world. I know even the speech of birds and the speech of beasts," and so he sat on, describing himself in many ways. "Rāvaṇa! Your mean arts and your mean powers look small before my husband. If you recognise one thing well, you will have learnt every art. Think how your mind would be if a stranger carried off your own Mandodarī," she said. "When you carry off another man's wife, have you given any thought to how many torments that man suffers, how many kinds of grief he suffers? In the very way you wish others to honour you, you must first try to honour others. Whatever you think it good for others to do, that good you must first do and show them. Only for your own selfish ends, out of your own Ahaṅkāra, you go on describing yourself like this; you make no effort at all to see the good and the bad of others. Hiding your own faults, you try to magnify faults that are not in others. This is contrary to the knowledge of the Ātma. When any hardship befalls others in any matter, in whatever way it comes, one must first feel it as one's own. Just as one suffers grief when losses befall one, so one must develop the feeling that others suffer the same grief when hardship befalls them. All your arts, lacking such power of discrimination, are mean arts. They are only physical arts; they are not true learning," she pronounced to this Rāvaṇa. She spoke one more word as well. "Rāvaṇa! I am Mother not to one alone; I am the Mother of the whole world. To you too I am equal to a mother. It is not right for you to torment such a Mother in this way. It does no honour to your learning."
Hanumān, who had recognised this truth, went to Rāvaṇa and taught him the Tattva of this Mother Divine.
This Sītā is the Mother of the world; look, She is a mother to you; having brought the world's Mother here, you have now taken sin upon yourself; with a single arrow Rāma will strike off your heads all at once; I give you good counsel, Rāvaṇa: this Laṅkā is yours no longer, you of evil ways! I spoke with Sītā, I gave her Rāma's precious ring; though I killed the wretched demons who guarded the grove, thinking me a sinner, the demons who keep the royal city fought me, taking me for a monkey; I give you good counsel, Rāvaṇa: this Laṅkā is yours no longer, you of evil ways!