Jesus is speaking to the Jews of his generation. Alternate translation: "You are an evil and adulterous generation who demands signs from me ... given to you" (See: [[rc://en/ta/man/jit/figs-123person]])
Here "adulterous" is a metaphor for people who are not faithful to God. Alternate translation: "unfaithful generation" or "godless generation" (See: [[rc://en/ta/man/jit/figs-metaphor]])
This double negative emphasizes that the sign of Jonah is the only sign that will be given. Alternate translation: "The only sign that will be given to it is the sign of Jonah" (See: [[rc://en/ta/man/jit/figs-doublenegatives]])