In plain words
She took her oil bath, picked up her bowl of pāyasam and went up to the terrace. In those days there were no fans or hair-driers, you see! So she went to the top of the terrace and, as she dried her hair, set her bowl of pāyasam on the wall. Just then a great eagle came and snatched the bowl away. Sumitrā stood stunned. The eagle carried the bowl of pāyasam off and let it fall on a mountain. Seeing it, Añjanā Devī herself ate the pāyasam in the bowl. As a result, Hanumān was born from her womb.
With the eagle snatching her bowl of pāyasam away, Sumitrā was at a loss. Grieving at her carelessness and afraid of what King Daśaratha would say, she came back down. She went to Kausalyā and Kaikeyī and told them what had happened. Then Kausalyā, comforting her: “Sister! You need not be troubled. I will give you half of my pāyasam,” she said. Kaikā too said she would give her half of her pāyasam. So great was the unity of co-wives in those days. At once they sent for a golden bowl, and Kausalyā poured into it half of her pāyasam and Kaikeyī half of hers, and they handed it to Sumitrā. Just then the priest called, and all three took their bowls of pāyasam and went. They received his blessings and ate the pāyasam. When nine months were complete, Rāma was born to Kausalyā. Bharata was born to Kaikā. To Sumitrā, though, two sons were born. “Why have two children been born to me alone?” she wondered. She realised that two sons had been born to her because that day, when the eagle snatched her bowl of pāyasam away, she had eaten half of Kausalyā's pāyasam and half of Kaikeyī's. ‘Lakṣmaṇa was born of the pāyasam Kausalyā gave. So he must follow Rāma.