You can make explicit why they want to see a sign. AT: "to see a sign from you that proves what you say is true" (See: [[rc://en/ta/man/translate/figs-explicit]])
# An evil and adulterous generation seeks for a sign ... given to it
Jesus is speaking to his present generation. AT: "You are an evil and adulterous generation who demands signs from me ... given to you" (See: [[rc://en/ta/man/translate/figs-123person]])
# adulterous generation
Here "adulterous" is a metaphor for people who are not faithful to God. AT: "unfaithful generation" or "godless generation" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# seeks for a sign
This request angers Jesus because of the religious leaders skeptical attitude about Jesus. He had already performed many miracles, but they still did not believe him. (See: [[rc://en/ta/man/translate/figs-explicit]])
# no sign will be given
This can be stated in active form. AT: "God will not give a sign" (See: [[rc://en/ta/man/translate/figs-activepassive]])