Hangul syllable ggwit

It spells one syllable; the word around it supplies the meaning.

뀥 combines ㄲ as its initial consonant, ㅟ as its vowel, and ㅌ as its final consonant. These Hangul jamo (letters used to build syllables) form a spelling unit, not a word that names an idea by itself.

The Hangul system behind this block is recorded in the Sejong Records in 1443. Hunminjeongeum, a book introducing the Korean letters and explaining how initial, middle, and final sounds combine, was published in 1446. Hangul was designed to represent Korean speech more directly than Chinese-character writing did. A possible influence from the square Phags-pa script, commissioned in 1265 and promulgated in 1269 for the Yuan empire, remains debated; that proposal does not show that this syllable descends from it.

What does 뀥 mean when someone sends it?

Read it as Korean text; the block alone does not reveal the sender’s tone.

By itself, this syllable does not tell you whether the message is a fragment or a typo. Ask which Korean word it belongs to before deciding what the sender meant.