He'll understand one day that he did everything for him..I believe there will be such a day..

He'll understand one day that he did everything for him..I believe there will be such a day..
He'll understand one day that he did everything for him..I believe there will be such a day..

He'll understand one day that he did everything for him..I believe there will be such a day..
将来的某一天,他就会明白他（另一个人）所为他做的一切.我相信,会有那么一天的.

总有一天他会明白他对他所做的一切...我相信会有这一天

:( 他总有一天会明白他为他做了所有的事儿。我相信这天总会来临。

总有一天，他（例如儿子？）会理解他（例如父亲？）所做的一切都是为了他（和第一个他是同一人）好……我确信会有这么一天的。