This means that he groaned or that he let out a long deep breath that could be heard. It probably shows Jesus's deep sadness that the Pharisees refused to believe him. See how you translated this in [Mark 7:34](../07/34.md).
Jesus is scolding them. This question may be written as a statement. Alternate translation: "This generation should not seek a sign." (See: [[rc://en/ta/man/translate/figs-rquestion]])
When Jesus speaks of "this generation," he is referring to the people who lived at that time. There Pharisees are included in this group. Alternate translation: "you and the people of this generation" (See: [[rc://en/ta/man/translate/figs-explicit]])