Learn Hardcore Korean: jigeum hoeuireul junbihago isseoyo.

을 is the object-marker particle. It tells you that 회의 (“meeting”) is the direct object of the verb phrase 준비하고 있어요 (“am preparing”). In Korean, every transitive verb usually needs either 을 or 를 (depending on whether the noun ends in a consonant or vowel) to mark its object.

Why isn't there an explicit subject like 저 or 나 in this sentence?

Korean often drops (omits) the subject when it’s clear from context. In English we say “I’m preparing a meeting right now,” but in Korean you don’t need 저 (“I”) or 나 (“I”) because listeners automatically understand who is doing the action if it makes sense in the situation.

What is the function of -고 있어요 in 준비하고 있어요?

-고 있다/있어요 is the progressive aspect marker in Korean, equivalent to English “be + –ing.”
• 준비하다 = “to prepare” (base verb)
• 준비하고 있다 = “to be preparing” (dictionary form)
• 준비하고 있어요 = polite present progressive
It emphasizes that the action is ongoing right now.

How is 지금 different from just saying 준비하고 있어요?

지금 means “now” or “right now.”
• Adding 지금 explicitly highlights the timing: “I am preparing the meeting right now.”
• Without 지금, the sentence 회의를 준비하고 있어요 still means “I’m preparing a meeting,” but it doesn’t stress that it’s happening at this exact moment.