"This has not prepared him well."
Translation:Esto no lo ha preparado bien.
I had the same question! Le works for to him/to her, the indirect object pronoun. What I didn't know is lo/la as the direct object pronoun isn't just for referring to an it, but also just to him/her if it's not TO him/her. "Lo veo" is I see him."Le canto" is I sing TO him/her. I just learned this, so research it, these are what helped me: https://www.spanishdict.com/answers/246672/le-vs.-lo-pronouns https://www.mytutor.co.uk/answers/5950/A-Level/Spanish/When-is-it-right-to-use-lo-la-and-le-in-Spanish/