mareun geollega eobseoseo jeojeun geollereul changmun yeope georeo dwosseo.

Because Korean changes descriptive verbs and verbs into noun-modifying forms when they come before a noun.

• 마르다 → 마른 = dry
• 젖다 → 젖은 = wet
• 걸레 = rag / cloth

So:

• 마른 걸레 = a dry rag
• 젖은 걸레 = a wet rag

This is very common in Korean. English often uses plain adjectives, but Korean often uses a verb-derived form before the noun.

없어서 comes from 없다 (to not exist / to not have) + -어서, which often means because or shows a reason/connection.

So:

• 마른 걸레가 없어서 = because there wasn’t a dry rag / since I didn’t have a dry rag

In this sentence, it gives the reason for the next action:

• there was no dry rag,
• so the speaker hung the wet rag by the window.

This is about the role of each noun in the sentence.

1. 마른 걸레가 없어서

Here, 마른 걸레 is the thing that does not exist / is not available, so it takes 가.

• X가 없다 = there is no X / I don’t have X

2. 젖은 걸레를 창문 옆에 걸어 뒀어

Here, 젖은 걸레 is the object being acted on, so it takes 를.

• X를 걸다 = to hang X

So:

• 마른 걸레가 없다 = there is no dry rag
• 젖은 걸레를 걸다 = to hang the wet rag

창문 옆에 means next to the window or beside the window.

Breakdown:

• 창문 = window
• 옆 = side
• 옆에 = at the side of / next to

The particle 에 is used here because it marks the location where something is placed.

So:

• 창문 옆에 걸어 뒀어 = I hung it next to the window / by the window

This is an important point.

• 걸다 = to hang
• 걸어 두다 = to hang something and leave it that way for later / for a purpose

So 걸어 뒀어 is a shortened spoken form of 걸어 두었어.

It suggests more than just the action of hanging. It implies:

• the speaker hung it up,
• and left it there intentionally.

In this context, it sounds like:

• I hung the wet rag by the window and left it there
  possibly so it could dry.

걸어 뒀어 is the natural contracted spoken form of 걸어 두었어.

The full form:

• 걸어 두었어

Common conversational contraction:

• 걸어 뒀어

This kind of contraction is extremely common in everyday Korean.

Other similar examples:

• 해 두었어 → 해 뒀어
• 넣어 두었어 → 넣어 뒀어
• 써 두었어 → 써 뒀어

So 걸어 뒀어 sounds natural and conversational.

Yes, the sentence is in the past tense overall.

The clearest past marker is in:

• 뒀어 = contracted from 두었어

That -었- is the past tense marker.

So:

• 걸어 뒀어 = hung it up and left it there / had hung it up

The first part, 마른 걸레가 없어서, does not need a separate past marker because the whole sentence is understood in context as describing what happened at that time.

Korean often omits subjects when they are obvious from context.

So instead of saying:

• 나는 마른 걸레가 없어서...

the speaker can simply say:

• 마른 걸레가 없어서...

The listener usually understands that the implied subject is I or we, depending on context.

This is very normal in Korean and often sounds more natural than stating the subject every time.

걸레 usually means a rag, cleaning cloth, or dishcloth-like cloth used for wiping. It often has a practical cleaning sense, not just any piece of fabric.

So in this sentence, it sounds like the speaker is talking about a cloth used for wiping or cleaning, not an ordinary towel or piece of clothing.

Korean word order is flexible, but the default pattern is often:

• object + location + verb

So:

• 젖은 걸레를 창문 옆에 걸어 뒀어

is very natural.

You could also say:

• 창문 옆에 젖은 걸레를 걸어 뒀어

This also sounds natural, but it gives a little more early emphasis to the location.

Because the verb comes at the end in Korean, other parts of the sentence can move around more than in English, as long as the particles make the roles clear.

Yes, there is a small nuance difference.

없어서

• sounds more like a neutral reason or natural cause-and-effect
• because there wasn’t a dry rag...

없으니까

• can sound a little more like the speaker’s reasoning or justification
• since there wasn’t a dry rag...

In this sentence, 없어서 sounds very smooth and natural because it simply explains why the next action happened.

Yes, very likely.

The sentence does not say directly so it would dry, but that idea is strongly suggested by:

• 창문 옆에 = by the window
• 걸어 두다 = hang and leave there intentionally

So a listener would naturally understand something like:

• there was no dry rag,
• so the speaker hung the wet one by the window,
• probably to let it dry.

That meaning is implied rather than explicitly stated.