i oreumagi saenggakboda hwolssin gireo.

They are doing two different jobs.

• The first 이 means this.
• The second -이 is the subject particle attached to 오르막.

So:

• 이 오르막 = this uphill / this incline
• 이 오르막이 = this uphill
  • is the subject of the sentence

A native-English-style breakdown would be:

• 이 = this
• 오르막 = uphill slope / incline
• -이 = subject marker

So the sentence starts with As for this uphill stretch... or more naturally This uphill stretch...

오르막 means an uphill slope, incline, or uphill stretch.

It refers to the part of a road, path, or hill that goes upward.

Examples:

• 오르막이 많아. = There are a lot of uphill sections.
• 오르막길 = uphill road/path

In this sentence, 오르막 is basically the thing being described as long.

Yes, but only slightly.

• 오르막 = uphill, incline, upward slope
• 오르막길 = uphill road/path

In many everyday situations, they are very close in meaning.
오르막길 can sound a little more concrete because 길 explicitly means road/path.

So:

• 이 오르막이 생각보다 훨씬 길어.
• 이 오르막길이 생각보다 훨씬 길어.

Both are natural. The second one may feel a bit more specific: This uphill road/stretch is much longer than I thought.

생각보다 means than I thought, than expected, or more literally than thought.

It is made from:

• 생각 = thought / thinking
• 보다 = than / compared to

So 생각보다 is a comparison phrase.

In natural English, you usually translate it as:

• than I thought
• than I expected

Even though English needs a subject like I, Korean often leaves that unstated when it is obvious from context.

Yes. You can think of it as a shortened everyday form.

A fuller expression could be something like:

• 내가 생각한 것보다 = than what I thought
• 생각했던 것보다 = than I had thought

But in real conversation, Korean often shortens this to just 생각보다.

So in this sentence:

• 생각보다 훨씬 길어
  = It’s much longer than I thought

This shorter form is extremely common and natural.

Because Korean very often omits subjects and pronouns when they are understood from context.

In English, you usually need to say:

• than I thought

In Korean, if it is obvious that the speaker means their own expectation, you can just say:

• 생각보다

Depending on context, it can mean:

• than I thought
• than we thought
• than expected

Korean relies more on context than English does.

훨씬 means much, far, or a lot in comparisons.

So:

• 길어 = is long
• 생각보다 길어 = is longer than I thought / is long compared to what I thought
• 생각보다 훨씬 길어 = is much longer than I thought

It strengthens the comparison.

Compare:

• 생각보다 길어. = It’s longer than I thought.
• 생각보다 훨씬 길어. = It’s much longer than I thought.

길어 is the casual/informal present tense form of 길다.

• 길다 = dictionary form, to be long
• 길어 = casual spoken form
• 길어요 = polite spoken form

So the sentence as given is informal:

• 이 오르막이 생각보다 훨씬 길어.

Polite version:

• 이 오르막이 생각보다 훨씬 길어요.

This suggests the speaker is talking casually to a friend, family member, or someone they are close to.

In Korean grammar, 길다 is usually called a descriptive verb or adjective-like verb.

In English, we would usually just think of it as an adjective:

• long

But in Korean, words like 길다, 크다, 예쁘다 behave like verbs in many ways, because they conjugate directly:

• 길다 → 길어
• 크다 → 커
• 예쁘다 → 예뻐

So 길어 means is long.

No. Here it means long, not steep.

So the sentence is saying the uphill stretch has a greater length/distance than expected.

If you want to say steep, you would use other words, such as:

• 가파르다 = to be steep
• 경사가 심하다 = the slope is steep/severe

So these are different:

• 이 오르막이 길어. = This uphill stretch is long.
• 이 오르막이 가파라. = This uphill stretch is steep.

Korean often puts the comparison phrase before the final descriptive word.

Sentence structure here is roughly:

• 이 오르막이 = this uphill stretch
• 생각보다 = than I thought
• 훨씬 = much
• 길어 = is long

So literally, it is something like:

• This uphill, than thought, much, is long.

But natural English reorders it as:

• This uphill stretch is much longer than I thought.

That is a very normal Korean pattern: subject + comparison phrase + adverb + descriptive verb

Yes, that is fine in many contexts.

A few natural English translations are:

• This uphill stretch is much longer than I thought.
• This incline is much longer than I expected.
• This hill is a lot longer than I thought.

Hill is not a word-for-word match, but it can sound natural depending on the situation.
If you want to stay closer to the Korean, uphill stretch or incline is better.

It sounds like something someone says while:

• hiking
• walking uphill
• biking
• driving up a mountain road
• climbing a long slope

The feeling is usually:

• I expected this uphill part to be shorter, but it keeps going.

So it carries a mild sense of surprise, and sometimes a little complaint or tiredness.