Jesus is emphasizing that what he has just said is important and may take some effort to understand and put into practice. The phrase "ears to hear" here is a metonym for the willingness to understand and obey. AT: "Let the one who is willing to listen, listen" or "The one who is willing to understand, let him understand and obey" (See rc://en/ta/man/translate/figs-metonymy).
# He who...let him
Since Jesus is speaking directly to his audience, you may prefer to use the second person here. AT: "If you are willing to listen, listen" or "If you are willing to understand, then understand and obey"(See rc://en/ta/man/translate/figs-123person).