Paul says basically the same thing twice for emphasis. AT: "he would realize that he is guilty of sin because he hears what you are saying" (See: [[rc://en/ta/man/translate/figs-parallelism]])
"The secrets of his heart" here is a synecdoche for "private inner thoughts." This can be stated in active form. AT: "God would reveal to him the secrets of his heart" or "He would recognize his own private inner thoughts" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-synecdoche]]).