baesugueseo akchwiga napnida.

배수구 means drain, drain opening, or drain outlet.

It breaks down like this:

• 배수 = drainage, draining water
• 구 = opening, mouth, entrance

So 배수구 is the place where water drains away, such as a sink drain, floor drain, or similar opening.

에서 marks the source or place something comes from / happens at.

In this sentence, 배수구에서 means from the drain.

So the idea is:

• 배수구에서 = from the drain
• 악취가 납니다 = a bad smell comes out / there is a bad smell

A native English speaker might expect 에, but 에서 is more natural here because the smell is understood as coming from that place.

냄새 is the general word for smell or odor. It can be neutral, good, or bad depending on context.

악취 specifically means a foul smell, stench, or bad odor.

So:

• 냄새 = smell
• 악취 = bad smell, stench

This makes 악취 stronger and more formal than just 냄새.

For example:

• 냄새가 나요 = There is a smell.
• 악취가 나요 = There is a horrible smell.

Because 악취 is the thing that is appearing / being emitted, so it acts as the subject, not the object.

The verb here is 나다, which often means to come out, to occur, or to be produced in expressions like smell, sound, sweat, etc.

So:

• 악취가 나다 = a bad smell occurs / comes out

This is a very common Korean pattern:

• 냄새가 나다 = a smell comes out
• 소리가 나다 = a sound comes out
• 땀이 나다 = sweat comes out

Even though English says It smells bad or There is a bad smell, Korean often uses this Noun + 가 나다 structure.

납니다 is the formal polite form of 나다.

In this sentence, 나다 does not mean to go out or to leave. Here it means something like:

• to come out
• to arise
• to be produced

So 악취가 납니다 literally means:

• A foul smell comes out
• more naturally, There is a bad smell
• or A bad smell is coming from it

This verb is very common with sensations and emissions:

• 소리가 납니다 = A sound is coming out / I hear a sound.
• 연기가 납니다 = Smoke is coming out.
• 열이 납니다 = I have a fever.
  (literally, heat is arising)

Yes, 납니다 is formal polite style.

More conversationally, you would usually hear:

• 배수구에서 악취가 나요.

Both are polite, but:

• 납니다 = more formal, often used in announcements, writing, customer service, reports, etc.
• 나요 = everyday polite speech

Very casual speech could be:

• 배수구에서 악취가 나.

No, that would sound unnatural.

The problem is that 배수구 is not the thing producing the grammar role of subject here. The sentence is built around:

• 배수구에서 = from the drain
• 악취가 = bad smell
• 납니다 = comes out / is occurring

So the natural structure is:

• 배수구에서 악취가 납니다.

If you want 배수구 to be the subject, you would need a different phrasing, such as:

• 배수구에서 냄새가 나요.
• 배수구가 냄새가 나요 is generally awkward
• better: 배수구 냄새가 나요 in very casual speech, or more clearly
• 배수구에서 냄새가 나요

Not exactly literally, but that is a very natural English translation.

The Korean structure is closer to:

• From the drain, a foul smell is coming out.

Natural English translations include:

• There’s a bad smell coming from the drain.
• A foul odor is coming from the drain.
• The drain smells bad.

So yes, that English meaning is fine, even though the Korean grammar is built differently.

Yes. That is very common.

Compare:

• 배수구에서 냄새가 납니다. = There is a smell coming from the drain.
• 배수구에서 악취가 납니다. = There is a foul smell coming from the drain.

Using 냄새 is less strong and more general.
Using 악취 sounds stronger, more explicit, and a bit more formal.

It is written 납니다, but in actual pronunciation it sounds closer to 남니다.

So:

• 납니다 → [남니다]

This happens because the final ㅂ sound in 납 changes before ㄴ.

The whole sentence is pronounced roughly like:

• 배수구에서 악취가 남니다

Romanization is only an approximation, but you may hear something like:

• baesugu-eseo akchwi-ga namnida

Because Korean often expresses ideas differently from English.

English commonly says:

• There is a bad smell coming from the drain.

Korean does not need a separate there is here. Instead, it uses the verb 나다:

• 악취가 납니다 = a bad smell comes out / occurs

So Korean expresses the same idea through the verb, rather than through an English-style there is construction.

It would be used when someone notices an unpleasant odor coming from a drain, for example:

• in a bathroom
• in a kitchen sink
• in a basement floor drain
• in a building maintenance context

Because 악취 and 납니다 are slightly formal, this sentence sounds especially natural in:

• maintenance reports
• customer complaints
• notices
• professional conversation

In everyday speech, someone might more naturally say:

• 배수구에서 냄새가 나요.
• 하수구에서 냄새가 나요. depending on the kind of drain

Both can relate to drains, but they are not always exactly the same.

• 배수구 = drainage opening, drain outlet
• 하수구 = sewer drain, sewage drain, gutter-like drain

In many everyday situations they may both be translated as drain, but:

• 배수구 often focuses on the drainage function
• 하수구 can sound more like a sewage or wastewater drain

So 배수구에서 악취가 납니다 sounds natural for a drain opening, while 하수구에서 악취가 납니다 could suggest a sewer-like drain or wastewater drain.