Learn Hardcore Korean: ojeone hoeuisireseo hoeuihaeyo. - I have a meeting in the meeting room in the morning.

오전에 = 오전 + 에. 에 marks the time when something happens: “in/on/at.”
회의실에서 = 회의실 + 에서. 에서 marks the place where an action occurs: “at/in (doing something).” Compare:
회의실에 있어요. = “I am in the meeting room.” (location/existence)
회의실에서 일해요. = “I work in the meeting room.” (place of action)

Why does the sentence say both 회의실 and 회의? Isn’t that redundant?

Not in Korean.

회의실 literally “meeting room” (회의 meeting + 실 room).
회의하다 means “to hold a meeting.”
So 회의실에서 회의해요 is perfectly natural: “In the meeting room, (we) hold a meeting.”
If the context already makes “meeting” obvious, you can sometimes shorten to 회의실에서 해요, but only when it’s crystal clear what “do it” refers to.

Do I need the object marker here, as in 회의를 해요?

Both are fine:

회의해요 (no object marker) — common because N + 하다 is a set verb.
회의를 해요 — also correct; a bit more explicit/neutral. Meaning difference is minimal in everyday speech.

What politeness level is -해요?

-해요: polite, neutral style used with most adults (coworkers, acquaintances).
-합니다: formal polite (presentations, announcements).
-해: casual (friends, younger people).
Honorific forms exist for subjects you respect, e.g., 회의하세요, 회의하십니다 (context-dependent).

What tense is 해요? Can it mean the future?

해요 is present, but with a time expression it often means a scheduled future:

오전에 회의해요. can be “I have a meeting this morning” (today’s schedule) or a general habit. To make future explicit: 오전에 회의할 거예요 / 회의가 있을 거예요.

Can I change the word order?

Yes, Korean is flexible, but the most natural is Time → Place → Action:

Natural: 오전에 회의실에서 회의해요.
Also okay: 회의실에서 오전에 회의해요. (a bit less typical)
With emphasis you can use topics: 오전에는 회의실에서 회의해요., 회의실에서는 오전에 회의해요. Keep adverbials before the verb; putting them after the verb is unnatural.

What’s the difference between 오전에 and 아침에?

오전 = “AM,” before noon (objective clock time).
아침 = “morning” as a part of the day (often early morning; can include breakfast time). So:
오전에 회의해요. = It’s before noon.
아침에 회의해요. = It’s in the morning period, often earlier in the day; slightly more casual/colloquial.

How is the whole sentence pronounced naturally?

오전에: [오전에]
회의: often [회이] (both [회의] and [회이] are standard)
회의실에서: [회이시레서] — the ㄹ in 실 links forward: 실+에서 → [시레서]
회의해요: [회이해요] Overall: roughly [오전에 회이시레서 회이해요]. Don’t worry if you hear 의 sounding like 이 here.

Is 회의해요 written together or with a space?

Together: 회의해요 (preferred when used as a set verb “to meet/hold a meeting”).
If you use the object marker: 회의를 해요 (space before 하다).
Avoid the in-between typo: “회의 해요” (no 를).

Who is the subject? It’s not stated.

Korean often drops obvious subjects. Here it’s usually understood as I or we from context.
You can add one if needed:

Is there another common way to say this?

Yes, using “there is a meeting”:

How do I make it a question or negative?

Why is 에 used with time but not with the place here?

Time takes 에: 오전에 = “in the morning.”
Place of action takes 에서: 회의실에서 = “at the meeting room (doing something).” For static location, use 에: 회의실에 있어요 (“I am in the meeting room”).

Does 오전에 mean “this morning,” “tomorrow morning,” or just “in the morning”?

By itself, it’s context-dependent. In daily talk, it often means “this morning” (if said on the same day), but to be clear add a day:

Is it okay to say 미팅 or 미팅룸 instead of 회의/회의실?

회의/회의실 are the safest, standard choices.
In many offices you will hear 미팅(하다) and 미팅룸; they’re common in business slang.
Be aware that 미팅 can also mean a “group blind date” in other contexts, so 회의 is clearer in general.