Learn Hardcore Korean: keompyuteo yeope hyudaeponi isseoyo. - There is a cell phone next to the computer.

It’s the polite present-tense form of the verb 있다, which means to exist or to have. In 휴대폰이 있어요, it literally means “the phone exists” (i.e. “there is a phone”).

Why does 휴대폰 take the subject marker 이/가 instead of 은/는?

With the verb 있다, the thing that exists is always marked with 이/가 (the subject marker). It tells us what exists.

Could I say 휴대폰은 컴퓨터 옆에 있어요 instead? What changes?

Yes. 은/는 marks 휴대폰 as the topic. 휴대폰은 컴퓨터 옆에 있어요 emphasizes “As for the phone…” and then gives its location. The original sentence emphasizes the location first (“By the computer…”).

Can I change the word order? For example, 휴대폰이 컴퓨터 옆에 있어요?

Absolutely. Korean allows flexible word order, especially with particles. 휴대폰이 컴퓨터 옆에 있어요 simply states the phone is next to the computer, with the phone mentioned first. The original order highlights the location before the thing that exists.

What is the difference between 있어 and 있어요?

있어 is the informal form (used with close friends or younger people).
있어요 is polite (suitable for strangers or more formal settings).

Can you omit 컴퓨터 or 휴대폰 if the context is clear?

Yes. In casual conversation, once the objects are understood, you can drop them:

옆에 있어요 (It’s next to [it])
휴대폰이 있어요 (There’s a phone [here])
But make sure listeners know what you’re referring to.

Are there other ways to say “next to” in Korean?

옆에 is the most common (side of).
곁에 is literary or slightly more formal (by the side of).
주변에 means around or in the vicinity of, which is broader than right next to.

Why can’t you say 컴퓨터 옆에서 휴대폰이 있어요?

The particle 에서 marks the place of action. Since 있다 expresses existence rather than an action, it takes 에. 옆에 is correct for location; 옆에서 would imply an action happening at the side.

How do I say “My phone is next to the computer”?

Add the possessive 제 (my) before 휴대폰:
제 휴대폰이 컴퓨터 옆에 있어요.