Learn Hardcore Korean: jeoneun jigeum samusireseo ilhago isseoyo.

저 is the humble form of “I,” and -는 is the topic particle. Together, 저는 means “as for me” or “I (am speaking about myself).” It sets 저 as the topic of the sentence.

Why don’t we use 나 instead of 저 for “I”?

나 is the informal or casual word for “I,” used among close friends or younger speakers. 저 is more polite and humble, appropriate in most everyday situations when you want to show respect or keep things neutral.

What does 지금 mean, and where does it go in the sentence?

지금 means “now” or “right now.” In Korean, time adverbs like 지금 typically come before the verb or clause they modify. Here, 저는 지금 사무실에서 일하고 있어요 literally orders as “I – now – at the office – working am.”

Why is the particle -에서 used with 사무실 instead of -에?

-에 indicates a static location (“at” / “in”). -에서 indicates the location of an action (“working at”). Since 일하다 (to work) is an action happening in the office, you need 사무실에서.

What does 일하고 있어요 mean, and how is it formed?

일하다 means “to work.” To express the present progressive (“am working”), you take the verb stem 일하-, add -고 있다, then adjust for polite speech.
• 일하-고 있다 = “be working”
• Polite present progressive = 일하고 있어요

Can I drop 저는 and just say 지금 사무실에서 일하고 있어요?

Yes. Korean often omits the topic or subject when it’s clear from context. So 지금 사무실에서 일하고 있어요 still means “I’m working in the office right now.”

What level of politeness is 일하고 있어요, and how can I change it?

-아/어요 endings (like 있어요) are the “informal polite” style used in daily conversation with people you don’t need to be overly formal with.
• To be more formal: 일하고 있습니다 (formal polite)
• To be casual: 일하고 있어 (informal casual)

If I want to say “I work in an office” as a general fact (not right now), how would I change the sentence?

Drop 지금 and switch to the simple present:
저는 사무실에서 일해요.
This means “I work in an office” as a habitual or general statement.