I can't tell youA polite or neutral way to say that you cannot provide information, either because you do not know it or because you cannot disclose it. The related past-tense form я не мог вам сказать means “I couldn't tell you.”
RU: К сожалению, я не могу вам сказать, где он сейчас.
EN: Unfortunately, I can't tell you where he is now.