This is the 17637th most frequent Russian word.
убил
"Убил" means "killed."
In this example, 'убил' is used figuratively to denote spending time in a relaxed or leisurely manner, not to be taken literally.
Он убил время, читая книгу.
He killed time by reading a book.
In this sentence, 'убил' indicates the act of causing the dragon's death, showing direct physical action.
Он убил дракона.
He killed the dragon.
Here, 'убило' metaphorically expresses the emotional impact of the news on her, equivalent to overwhelming or emotionally incapacitating.