Hangul syllable Ssweoj

Use a Korean input method (IME): enter ㅆ, ㅝ, then ㅈ.

On the common two-set layout, the input method joins the initial consonant, vowel, and final consonant as you type. To form ㅝ, enter ㅜ then ㅓ; physical keys vary by layout.

ssweoj is the Unicode label built from the short names of the block's jamo, not a Latin-letter keyboard command.

What does 쒖 mean?

By itself, it gives no clear message.

Read it as part of the Korean word around it. The block combines initial ㅆ, vowel ㅝ, and final ㅈ. Unicode can also represent the same syllable as the separate Hangul letters ᄊ + ᅯ + ᆽ, which some apps may display separately.

Where did Hangul syllable blocks come from?

They group Korean consonant and vowel letters into one syllable block.

Hangul was devised as a writing system for Korean speech, letting it represent Korean sounds and grammar more directly than Chinese characters. The first record appears in the Sejong Annals in 1443; in 1446, an explanatory guide to the new letters, Hunminjeongeum, was published.

Its later uses included translations, pronunciation guides, household writing, and public notices. The modern spelling system was based on a 1933 proposal and partly revised in 1988.