‘-은/ㄴ/는*’ is used before a noun to modify the noun. It is attached to an adjective word stem. When the word stem ends in a vowel, ‘ㄴ’ is used. When it ends in a consonant, ‘-은’ is used. When the adjective ends with ‘있다/없다’, then ‘-는’ is used.
● 짧은 치마를 샀어요. (I bought a short skirt.)
● 짠 음식을 먹지 마세요. (Don’t eat a salty food.)