A batch of adjectives end in ㅂ. Before a vowel ending, that ㅂ becomes 우.
덥다 → 더 + 우 + 어요 → 더워요
These are weather-and-taste words, which is exactly what beginners talk about.
덥다to be hot · 더워요
춥다to be cold · 추워요
맵다to be spicy · 매워요
어렵다to be difficult · 어려워요
쉽다to be easy · 쉬워요
맛있다to be tasty · 맛있어요 — *regular, no change*
Not every ㅂ stem changes. 입다 (to wear) and 좁다 (to be narrow) are regular: 입어요, 좁아요. There is no way to tell by looking — you learn which ones change as you meet them. The good news is that the irregular ones are mostly adjectives, and the common ones fit on the list above.
오늘 너무 더워요.It’s so hot today.
이 음식 좀 매워요.This food is a bit spicy.
한국어가 어려워요.Korean is difficult.
연습 · Practice
이 레슨에는 풀어 보는 문제가 7개 있습니다. 앱에서 하나씩 맞히며 넘어갑니다. 7 exercises come with this lesson — open it to work through them.