Learn Hardcore Korean: aiga sopa-e anja isseoyo. - A child is sitting on the sofa.

-가 marks the noun as the subject of the sentence (the one doing or being in the state).
You use -가 after a vowel-ending noun like 아이; if the noun ended in a consonant, you’d use -이 instead.

Why is 소파 followed by -에?

The particle -에 marks a location.

소파에 literally means “at/on the sofa.”
Whenever you want to say someone is doing something in or at a place, you stick -에 onto the place noun.

What does 앉아 있어요 literally mean?

앉아 있어요 is the present progressive/state expression “is sitting.”

앉아 comes from the verb 앉다 (to sit) in its connective form (stem + -아).
있어요 is from 있다 (to exist/be), giving the sense of “to be in the state of sitting.”

Why do we say 앉아 있어요 instead of simply 앉아요?

앉아요 means “sit down” or “I/you/we sit” (the action of sitting).
앉아 있어요 emphasizes the ongoing state (“is/are sitting”) rather than the action itself.

How is the progressive form 앉아 있다 constructed?

Take the verb stem: 앉- from 앉다.
Add the connective vowel -아 (because the stem ends in an ㅏ vowel): 앉 + 아 → 앉아.
Attach 있다 to show the continuous/state: 앉아 있다.
Conjugate politely: 앉아 있어요.

What politeness level does 앉아 있어요 convey?

It’s the standard polite (존댓말) form used in everyday conversation when speaking to strangers, acquaintances, or anyone you’re not extremely close with.

Could I say 아이는 소파에 앉아 있어요 instead of 아이가 소파에 앉아 있어요?

Yes, but there’s a nuance:

아이가 (subject marker) emphasizes “the child” as new or important information.
아이는 (topic marker) shifts the focus to “as for the child,” possibly implying a contrast (e.g., while others are standing, the child is sitting).

Is 소파 a native Korean word?

No, 소파 is a loanword from English sofa. Koreans sometimes also say 쇼파 with a “yo” sound, but both forms are understood.