Hun beskriver sin nye arbejdsplads som lys og rolig.

Because the workplace belongs to the subject of the sentence: hun.

In Danish, sin/sit/sine are reflexive possessive forms. They are used when the owner is the same person as the subject.

• Hun beskriver sin nye arbejdsplads ... = She describes her own new workplace ...
• Hun beskriver hendes nye arbejdsplads ... usually means she describes another woman’s new workplace.

This is one of the most important differences from English, because English uses her for both meanings.

Beskriver is the present tense of the verb at beskrive = to describe.

So:

• at beskrive = to describe
• beskriver = describes / is describing

In Danish, the present tense is often made by adding -r to the infinitive:

• at komme → kommer
• at arbejde → arbejder
• at beskrive → beskriver

In this sentence, beskriver means describes.

Because the adjective comes before a noun that is introduced by a possessive word like sin.

Compare:

• en ny arbejdsplads = a new workplace
• sin nye arbejdsplads = her new workplace

After possessives like min, din, sin, hendes, vores, adjectives usually take the -e form:

• min gamle bil
• deres store hus
• sin nye arbejdsplads

So nye is the correct form here.

Because Danish normally does not use an article together with a possessive in this kind of phrase.

So you say:

• sin nye arbejdsplads
• hendes bil
• min ven

Not:

• sin den nye arbejdsplads
• hendes en bil

This works much like English:

• her workplace not
• the her workplace

The possessive already does the job of identifying the noun.

Arbejdsplads is a compound noun, which is very common in Danish.

It is made from:

• arbejde = work
• plads = place

Together:

• arbejdsplads = workplace

Danish often writes compound nouns as a single word, where English may also use one word, two words, or a hyphen depending on the expression.

Also, arbejdsplads is a common-gender noun:

• en arbejdsplads

That matters for adjective agreement later in the sentence.

Here som means as.

The pattern is:

• beskrive noget som ... = describe something as ...

So:

• Hun beskriver sin nye arbejdsplads som lys og rolig. = She describes her new workplace as bright and calm.

Without som, the sentence would sound wrong in standard Danish.

Because they agree with arbejdsplads, which is singular and common gender.

In Danish, adjectives used like this often match the noun they describe.

Since arbejdsplads is:

• singular
• common gender
• indefinite in form

the adjectives stay in their basic form:

• lys
• rolig

Compare:

• en arbejdsplads → lys og rolig
• et kontor → lyst og roligt
• arbejdspladser → lyse og rolige

So the sentence uses the correct forms for en arbejdsplads.

Because roligt would be the form used with a neuter singular noun, an et-word.

But arbejdsplads is an en-word:

• en arbejdsplads → rolig
• et kontor → roligt

So:

• en lys og rolig arbejdsplads
• et lyst og roligt kontor

The same agreement applies here after som.

Not if you mean that it is her own workplace.

If the subject is hun and the workplace belongs to that same person, standard Danish uses sin:

• Hun beskriver sin nye arbejdsplads som lys og rolig.

If you say:

• Hun beskriver hendes nye arbejdsplads ...

it normally sounds like the workplace belongs to another woman, not to the subject herself.

For learners, a good rule is:

• use sin/sit/sine when the possessor is the subject
• use hans/hendes/deres when it is someone else

The basic structure is:

• Hun = subject
• beskriver = verb
• sin nye arbejdsplads = object
• som lys og rolig = complement describing the object

So the pattern is roughly:

Subject + verb + object + som + description

This is normal Danish main-clause word order.

Also remember that Danish is a V2 language, which means the finite verb usually comes in the second position in a main clause. For example:

• Hun beskriver sin nye arbejdsplads som lys og rolig.
• I dag beskriver hun sin nye arbejdsplads som lys og rolig.

When I dag is moved to the front, beskriver still stays in second position.

A rough English-friendly pronunciation could be:

hoon beh-SKREE-ver seen NY-uh AR-byes-plads som lees ow ROH-lee

A few notes:

• Hun has a vowel that does not exactly match English.
• y in nye and lys is a front rounded vowel, which many English speakers find difficult.
• arbejdsplads is a compound, and the first part can sound reduced in fast speech.
• Danish pronunciation is often much less phonetic than spelling suggests.

If you want to practice it piece by piece:

• Hun
• beskriver
• sin nye
• arbejdsplads
• som lys og rolig

That is usually easier than trying the whole sentence at once.