What is the meaning of ?

a seal or sigil carved into a jewel

more specifically, such a seal belonging to the Chinese emperor of the Qin Dynasty or later, or belonging to the Japanese emperor

八尺瓊曲玉 (Yasakani no Magatama), the jewel that is one of the three sacred treasures comprising the Imperial Regalia of Japan

the emperor's personal seal or sigil or the national seal or sigil used for state business

the mark made by such a seal or sigil

八尺瓊勾玉 (Yasakani no Magatama), one of the sacred treasures comprising the Imperial Regalia of Japan

all three of the sacred treasures

a mark or seal indicating imperial status

a sacred item indicating imperial status

the emperor's personal seal or sigil

Source: wiktionary.org