Hangul syllable Jjac

It is one Hangul syllable block, not a word by itself.

Korean syllable blocks combine consonant and vowel letters, called jamo. Here the parts are ㅉ + ㅏ + ㅊ: ㅉ starts the block, ㅏ is the vowel, and ㅊ closes it. “Jjac” is a romanized label for the syllable, not a translation. The block alone does not tell you a word-level meaning; read it with the surrounding Korean.

Where did 짳 come from?

It uses a syllable system designed for writing Korean.

Hangul began development under King Sejong in 1443; the Hunminjeongeum, a guide explaining the new letters, was published in 1446. These are dates for the writing system, not this exact syllable.

Hangul was designed for Korean sounds and grammar, so people could write Korean without first learning Chinese characters. Hanja, Chinese characters also used in Korean writing, remained alongside Hangul but do not supply this block's components. Hangul spread through commoners' writing, women's letters, Buddhist publications, novels, and official documents.

How do I type 짳?

On a standard Korean 2-set keyboard, press Shift+W, K, then C.

That enters ㅉ, ㅏ, ㅊ in order; Korean input software combines them into 짳. On a phone or a different keyboard layout, the keys may differ.