Meiji Shrine is a Shinto Shrine. Shinto is a Japanese traditional faith.
Shinto is a polytheist religion with no sacred scripts. Its gods are called kami. Kamis are the forces of nature: fire, wind, rain, mountains, trees, rivers, and so on.
Men become Kami when they die. Some popular personalities are worshipped in their own shrines. In the Shinto Shrines followers of this religion can buy talismans.