Learn Hardcore Korean: keompyuteo oenjjoge hyudaeponi isseoyo. - There is a cell phone to the left of the computer.

The particle 에 marks the location where something exists or happens. In 왼쪽에, it turns 왼쪽 (left side) into “at the left side,” so 왼쪽에 = at/to the left.

Why is the subject marker 이 used after 휴대폰 and not 가?

Korean has two subject markers, 이 and 가. You use 이 after a consonant-ending noun and 가 after a vowel-ending noun. Since 휴대폰 ends in the consonant ㄴ, it takes 이. Both mean “the subject,” but follow different sound rules.

What’s the difference between using subject markers 이/가 and topic markers 은/는 here?

이/가 introduces new information or focuses on existence (“there is…”).
은/는 marks the topic or what you’re talking about, often implying contrast or known info.
In an existential sentence like this, 휴대폰이 있어요 states “There is a cell phone.” If you said 휴대폰은 있어요, it’d sound like “As for the phone, it exists (but maybe something else doesn’t).”

What part of speech is 있어요, and why is it used?

있어요 is the polite present-tense form of the verb 있다, which means “to exist” or “to have.” In location sentences it expresses that something exists at a place. Without it, you wouldn’t convey existence or location.

Is the word order in 컴퓨터 왼쪽에 휴대폰이 있어요 fixed? Could you say 휴대폰이 컴퓨터 왼쪽에 있어요?

Korean word order is relatively flexible. Both versions are correct:

컴퓨터 왼쪽에 휴대폰이 있어요 emphasizes where first.
휴대폰이 컴퓨터 왼쪽에 있어요 emphasizes what exists first.
In both cases, the location phrase + subject + verb pattern remains.

How would you ask “Where is the cell phone?” using this structure?

Replace the specific location with 어디에 (where + location particle):
• 휴대폰이 어디에 있어요?
Literally “Cell phone where-at is?”

What’s the difference between 컴퓨터 옆에 and 컴퓨터 왼쪽에?

옆에 means beside/next to, without specifying left or right.
왼쪽에 means on the left side specifically.
Use 옆에 for general adjacency; 왼쪽에 or 오른쪽에 to be precise.

How would the sentence change if the phone were to the right of the computer?

Simply swap 왼쪽 for 오른쪽:
• 컴퓨터 오른쪽에 휴대폰이 있어요 (“There’s a cell phone on the right side of the computer.”)

What level of politeness does ending with -있어요 convey, and are there alternatives?

• -있어요 = standard polite (informal polite) form.
• In formal speech or writing you’d use 있습니다.
• Among close friends or family you can drop 요 and say 있어 (informal).

Can you omit 휴대폰이 or 컴퓨터 if context is clear?

Yes. In a conversation where both items are understood, you could say simply:
• 왼쪽에 있어요. (“It’s on the left.”)
But in isolation or for clarity, you need the full 컴퓨터 왼쪽에 휴대폰이 있어요.