Jesus is emphasizing that what he has just said is important and may take some effort to understand and put into practice. The phrase "has an ear" here is a metonym for the willingness to understand and obey. Alternate translation: "Let the one who is willing to listen, listen to" or "The one who is willing to understand, let him understand and obey" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Since Jesus is speaking directly to his audience, you may prefer to use the second person here. Alternate translation: "If you are willing to listen, listen to" or "If you are willing to understand, then understand and obey" (See: [[rc://en/ta/man/jit/figs-123person]])
This refers to anyone who conquers. Alternate translation: "anyone who resists evil" or "those who do not agree to do evil" (See: [[rc://en/ta/man/jit/figs-genericnoun]])