gyeolhoneun insaengeseo jungyohan irieyo.

은/는 is the topic particle. It marks 결혼 as the thing the sentence is talking about: as for marriage...

So 결혼은 인생에서 중요한 일이에요 feels like:

As for marriage, it is an important matter in life.

If you used 결혼이, the nuance would be a bit more like marriage is the thing that is important in life, with stronger subject focus. In many everyday sentences, both can be possible, but 은/는 is very natural here because the speaker is presenting a general statement about marriage.

Here, 인생에서 means in life or in one's life.

The particle 에서 can mark the scope, setting, or area within which something applies. In this sentence, it means something like:

within life / in the context of life

So:

• 인생에서 중요한 일 = an important matter in life

This is a very common use of 에서 beyond just physical location.

중요하다 means to be important.

When a descriptive verb (often called an adjective in Korean learning materials) comes before a noun, it changes into an attributive form.

So:

• 중요하다 = to be important
• 중요한 = important + noun

Here it modifies 일:

• 중요한 일 = an important thing / an important matter

This is similar to how English uses an adjective before a noun.

Not here. 일 can mean different things depending on context:

• work / job
• thing / matter / affair

In this sentence, 중요한 일 means an important thing or an important matter, not important work.

So 결혼은 인생에서 중요한 일이에요 means marriage is an important matter in life.

This is 일 + 이에요, the polite form of 이다 (to be).

Breakdown:

• 일 = thing, matter
• 이에요 = polite is

So:

• 일이에요 = it is a thing/matter

But in the sentence, it appears as 일이에요 after 중요한:

• 중요한 일이에요 = it is an important thing/matter

The 이 here is part of 이에요, not the subject particle 이/가.

A useful contrast:

• 학생이에요 = (someone) is a student
• 중요한 일이에요 = it is an important matter

Because 일 ends in a consonant (ㄹ), it takes 이에요 rather than 예요.

Basic rule:

• noun ending in a consonant + 이에요
• noun ending in a vowel + 예요

Examples:

• 학생이에요
• 책이에요
• 의사예요
• 학교예요

Since 일 ends in a consonant sound, 일이에요 is correct.

Yes, but the meaning and structure are a little different.

• 결혼은 인생에서 중요한 일이에요
  = Marriage is an important thing/matter in life.

• 결혼은 인생에서 중요해요
  = Marriage is important in life.

The second one is shorter and more direct.
The original sentence sounds slightly more formal or explanatory because it uses 중요한 일 (an important matter).

Both are natural.

It can mean both depending on context.

• 인생 = life, often in a broad or human-life sense
• in many sentences, it can also feel like one's life

Here, 인생에서 is naturally understood as in life or in a person's life. It is a broad, general statement rather than referring to one specific person's life.

이에요/예요 is polite, standard spoken Korean.

It is appropriate in:

• conversation
• class
• polite everyday speech
• many written explanations for learners

A more formal style would be:

• 결혼은 인생에서 중요한 일입니다.

A more casual style would be:

• 결혼은 인생에서 중요한 일이야.

So the original sentence is polite and natural.

A natural pronunciation is roughly:

겨로는 인생에서 중요항 이리에요

A few helpful pronunciation notes:

• 결혼은 sounds like 겨로는
• 중요한 is pronounced close to 중요한
• 일이에요 often sounds like 이리에요 in natural speech

You do not need to force every written sound exactly as spelled; Korean pronunciation often becomes smoother in connected speech.

Yes, that is a useful literal way to understand it.

• 결혼 = marriage
• 은 = topic marker

So 결혼은 is literally something like:

as for marriage

That literal gloss helps explain the grammar, but in natural English translation you would usually just say:

Marriage is...

Korean does not have articles like a, an, and the.

So 중요한 일 can mean:

• an important thing
• the important thing
• important matter(s)

The exact meaning depends on context. In this sentence, English naturally uses an important matter or simply important.

That is why Korean learners often need to remember that Korean nouns usually appear without articles.