What is the meaning of 薩埵?

sentient beings, living things

Short for 菩提薩埵菩提萨埵 (pútísàduǒ, “bodhisattva”).

sentient beings, all living things; by extension, the world

Short for 菩提薩埵 (bodai-satta): bodhisattva

Short for 菩薩王子 (Satta-ōji): name of a past reincarnation of the Gautama Buddha (Can we verify this sense?)

Short for 金剛菩薩 (Kongōsatta): Vajrasattva

Source: wiktionary.org