Gardinet er blødt og hænger stille.

Because -et makes the noun definite singular for a neuter noun.

• et gardin = a curtain
• gardinet = the curtain

So gardin is the basic dictionary form, and gardinet means the curtain.

In Danish, nouns are either common gender or neuter. You usually learn this from the article:

• en
  • noun = common gender
• et
  • noun = neuter

Since the word is et gardin, it is neuter. That is why the definite form is gardinet, not gardinen.

Because the adjective is describing a neuter singular noun in a predicate structure after er.

• Gardinet er blødt = The curtain is soft

The basic form is blød, but with a neuter singular noun it becomes blødt.

Compare:

• En pude er blød = A pillow is soft
• Et gardin er blødt = A curtain is soft
• Gardinerne er bløde = The curtains are soft

So the -t agrees with the neuter noun gardinet.

Because the same subject, gardinet, applies to both parts of the sentence.

• Gardinet er blødt og hænger stille.

This is like English:

• The curtain is soft and hangs still.

You do not need to repeat gardinet unless you want special emphasis.

Hænger is the present tense of hænge = to hang.

In Danish, the simple present often covers both ideas that English separates into:

• hangs
• is hanging

So hænger can mean either, depending on context.

Here:

• Gardinet hænger stille = The curtain hangs still / The curtain is hanging still

Danish does not usually need a special progressive form like English is hanging.

Here stille functions adverbially and means something like:

• still
• quietly
• without movement

So hænger stille means the curtain is hanging in a calm, unmoving way.

Be careful: stille can also be an adjective in other sentences, meaning quiet or calm. Here it describes how it hangs, so it works like an adverb.

Not all Danish adverbs are formed with -t in a simple way.

Many adjectives can form an adverb with -t, but adjectives ending in -e often keep the same form:

• stille = quiet/calm
• adverbially: stille

So:

• Han taler stille = He speaks quietly
• Gardinet hænger stille = The curtain hangs still

No, this is normal Danish main-clause word order:

• Gardinet = subject
• er = verb
• blødt = complement
• og hænger stille = coordinated second verb phrase

A simple breakdown is:

• Gardinet = The curtain
• er blødt = is soft
• og hænger stille = and hangs still

This is very straightforward Danish sentence structure.

Yes, blødt is tricky for English speakers.

A few useful points:

• ø is a vowel that does not exist in English
• the d in many Danish words is often soft and not pronounced like a full English d
• the final -t is heard

So blødt is not pronounced the way an English speaker might expect from the spelling. The important thing is to listen carefully to native audio and imitate it as a whole word rather than sounding out each letter separately.

Yes, but it means something different.

• Gardinet er blødt og stille = The curtain is soft and quiet/calm
• Gardinet er blødt og hænger stille = The curtain is soft and hangs still

In the original sentence, stille describes the action hænger. In your alternative sentence, stille describes the noun gardinet directly as another adjective.