This seal was discovered the day before Halloween, 2008, in Jerusalem. It is dated to the seventh century BC, in the time of Manasseh or Josiah, kings of Judea. If archaeology interests you, you can learn more at the Israel Antiquities Authority site.
The seal is a reverse image, because it is meant to leave an impression when stamped in clay or wax. Hebrew is written from right to left, but you can read the mirror image of the letters above from left to right: L-H-G-B, “for Hagab.” The script uses the archaic alphabet that the Hebrews shared with the Phonecians.