'Sign' in the Bible

Then a great sign appeared in heaven: a woman clothed with the sun, and with the moon under her feet, and on her head was a crown of twelve stars.

Then another sign appeared in heaven: a huge red dragon that had seven heads and ten horns, and on its heads were seven diadem crowns.

Then I saw another great and astounding sign in heaven: seven angels who have seven final plagues (they are final because in them God's anger is completed).