Hun holder masken.

Holder is the present tense form of the verb å holde.

• å holde = to hold / to keep
• holder = holds / is holding / keeps

So:

• Hun holder masken = She holds / is holding / keeps the mask

Unlike English, Norwegian does not change the present tense depending on the subject:

• jeg holder
• du holder
• hun holder
• vi holder

The infinitive holde is the dictionary form, not the form you use here.

The ending -en marks the noun as definite singular.

• en maske = a mask
• masken = the mask

In Norwegian, the is usually attached to the noun instead of written as a separate word. So masken literally means the mask.

It can be both, depending on context.

Literal meaning:

• She is physically holding a mask.

Idiomatic meaning:

• She keeps a straight face.
• She hides her feelings.
• She keeps up appearances.

The expression å holde masken is a common idiomatic phrase, so many learners meet it in that figurative sense.

Because Norwegian usually puts the definite article onto the noun itself.

Compare:

• en bil = a car
• bilen = the car

So in this sentence:

• masken already includes the meaning of the mask

You do not say the masken or anything similar. The ending does the job.

This is the normal Norwegian main-clause order:

subject + verb + object

• Hun = subject
• holder = verb
• masken = object

So:

• Hun holder masken

This is the most basic and natural order for a simple statement.

Yes, but it changes the meaning.

• Hun holder en maske = She is holding a mask
  This sounds literal and refers to a mask, not a specific or idiomatic one.

• Hun holder masken = She holds the mask or, very often, the idiomatic She keeps a straight face / hides her feelings

So en maske is possible, but it is not the same expression.

Yes. Norwegian present tense often covers both ideas.

So Hun holder masken can mean:

• She holds the mask
• She is holding the mask

The exact English translation depends on context. Norwegian does not need a separate form like English is holding in many cases.

A rough guide is:

• Hun ≈ hoon, but with a Norwegian u sound that does not exist exactly in English
• holder ≈ HOL-der
• masken ≈ MAHS-ken

A very approximate full pronunciation could be:

hoon HOL-der MAHS-ken

A few notes:

• The h in hun is pronounced.
• The o in holder is a long vowel.
• The a in masken is broad, like ah.

Exact pronunciation varies a bit by dialect.

For a negative sentence, add ikke:

• Hun holder ikke masken = She does not keep a straight face / She is not holding the mask

For the past tense, use holdt:

• Hun holdt masken = She kept a straight face / She held the mask

So the key forms are:

• å holde = infinitive
• holder = present
• holdt = past