Yi syllable Xiet

It means “what” or “which” in Nuosu Yi. ꑡ is a question syllable in the Liangshan standard; a Nuosu Yi word list glosses it as “what; which.” The rest of the sentence tells you whether it asks about an unknown thing or a choice.

That reading belongs to the Liangshan standard, one regional tradition among Yi writing systems. Earlier forms varied by region; some used signs for words or ideas, while this standard writes syllables by sound.

How did the Yi script develop?

Yi writing has regional histories; Liangshan is one standardized form. Nuosu origin stories link the script with Aki, one of the figures in those stories. A surviving inscription in Yi and Chinese on a bronze bell is dated 1485; that date shows the writing was already in use, not when it began.

In traditional Yi writing, bimo—Yi religious specialists—transmitted texts for ritual, magic, healing and family histories. The modern Liangshan standard was devised in 1974 and officially promulgated in 1980 to support literacy; it later appeared in official documents, newspapers and literature.

Yi writing is its own regional tradition, not a branch of Chinese characters or the Tibetan, Burmese or Tai scripts.

Someone sent me ꑡ—what should I read?

Only read it as a question word in Nuosu Yi text. There, it can ask “what?” or “which?”; a lone ꑡ outside that language context does not reveal what the sender intends. Treat it as written language and ask for context if needed.