'Generation' in the Bible

He sighed deeply in his spirit, and said, "Why does this generation seek a sign? Most certainly I tell you, no sign will be given to this generation."

For whoever will be ashamed of me and of my words in this adulterous and sinful generation, the Son of Man also will be ashamed of him, when he comes in the glory of his Father with the holy angels."

He answered him, "Unbelieving generation, how long shall I be with you? How long shall I bear with you? Bring him to me."

Most certainly I say to you, this generation will not pass away until all these things happen.