Learn Hardcore Korean: jibe keompyuteoga isseoseo onrain sueobeul deureoyo. - I have a computer at home, so I attend online classes.

집에 marks the location of 있다 (to exist)—you’re saying “there is a computer at home.” It’s not describing where you take the class (for that you would use 집에서 온라인 수업을 들어요), but rather where the computer is.

What does -이 있어서 mean in 컴퓨터가 있어서?

This is the existence verb 있다 plus the connective -아서/어서, which here expresses reason: “Because I have a computer…” Literally, 컴퓨터가 있어서 = “there is a computer (so)…”

Why is the subject particle -가 used with 컴퓨터 instead of the topic particle -는?

-가 often introduces new or important information and pairs naturally with 있다 (existence). If you said 컴퓨터는, you’d be emphasizing “as for the computer (I’ve already mentioned earlier)…” Here you’re simply stating “a computer exists,” so 컴퓨터가 is more neutral.

Can I use 컴퓨터가 있으니까 instead of 컴퓨터가 있어서?

Yes, both -아서/어서 and -으니까 can express cause (“because”).
• -아서/어서 is more descriptive and neutral—just stating a reason.
• -으니까 can feel a bit stronger, sometimes suggesting a conclusion or recommendation.
In daily speech either is fine: 컴퓨터가 있으니까 온라인 수업을 들어요.

Why is 을 used after 온라인 수업 (온라인 수업을 들어요)?

The verb 들다 (to take/listen to) requires a direct object. 수업 is what you’re taking, so you mark it with the object particle -을.

Why do we use 들어요 (to take/listen to) instead of 배워요 (to learn)?

In Korean, “to take a class” is usually expressed as 수업을 듣다 (literally “listen to a class”). 배우다 means “to learn” more generally, but the set phrase for “attending/taking classes” is 수업을 듣다.

Why is there no subject like 저는 or 내가 at the start?

Korean often drops the subject when it’s obvious from context. Here the speaker (“I”) is clear, so you can leave it out for a more natural flow.

Could I say 집에 컴퓨터가 있어서 온라인 수업을 받아요?

You could, but it’s less common. 수업을 받다 means “to receive instruction,” which is correct but more formal or passive-sounding. Most Koreans say 수업을 듣다 for “take a class.”