Stoltheten hennes er tydelig.

Because when a possessive comes after the noun in Norwegian, the noun is usually put in the definite form.

So:

• stolthet = pride
• stoltheten = the pride
• stoltheten hennes = her pride

This is a very common Norwegian pattern:

• boka mi = my book
• huset deres = their house
• stoltheten hennes = her pride

So the -en ending is doing important grammatical work here.

Yes. Hennes stolthet is also correct.

There are two common ways to express possession:

• stoltheten hennes
• hennes stolthet

Both can mean the same thing, but they do not feel exactly the same.

A simple rule of thumb:

• noun + possessive (stoltheten hennes) is very common and often the most neutral/natural choice in everyday Norwegian
• possessive + noun (hennes stolthet) can sound a bit more formal, literary, or emphatic

Also notice the noun form changes:

• stoltheten hennes
• hennes stolthet

Not hennes stoltheten.

Because sin/sitt/sine is a reflexive possessive, and it refers back to the subject of the clause.

In this sentence, the subject is:

• Stoltheten hennes

So the grammatical subject is stoltheten, not hun.

That means sin cannot refer to her here. You need hennes.

Compare:

• Hun viste stoltheten sin. = She showed her own pride.
  Here the subject is hun, so sin works.

But in:

• Stoltheten hennes er tydelig.

the subject is stoltheten hennes, so hennes is correct.

The base form is stolthet.

You can think of it like this:

• stolt = proud
• stolthet = pride

So stolthet is a noun related to the adjective stolt.

In the sentence, that noun appears in the definite singular form:

• stolthet → stoltheten

Because tydelig is a predicative adjective here: it comes after er and describes the subject.

Structure:

• Stoltheten hennes = subject
• er = verb
• tydelig = adjective

In this sentence, tydelig is the normal form to use.

A helpful extra point: adjectives ending in -ig usually do not add -t in the neuter singular in Bokmål, so you also get forms like:

• Det er tydelig.

And in plural/definite contexts you often get -e:

• tydelige tegn = clear signs

Here tydelig means something like:

• clear
• obvious
• evident
• noticeable

So the sentence is saying that her pride can be clearly seen or felt.

In this context, evident or obvious is often the most natural English match.

Yes. This is normal Norwegian main-clause word order.

The sentence is:

• Stoltheten hennes = first element
• er = finite verb
• tydelig = complement

Norwegian main clauses normally follow the V2 rule, which means the finite verb comes in the second position.

Since the whole subject phrase Stoltheten hennes counts as one unit, er correctly comes right after it.

A useful learner-friendly approximation is:

• stoltheten ≈ STOHL-the-ten
• hennes ≈ HEN-nes

The most important pronunciation point is this:

• the th in stolthet is not the English th sound in think or this

Instead, it is basically a t followed by an h at the start of the next syllable:

• stolt-het
• stol-the-ten

So do not pronounce it like English th /θ/ or /ð/.

Here hennes is a possessive form, meaning her.

It shows ownership or relationship:

• hennes stolthet = her pride
• stoltheten hennes = her pride

So it works like English her, but Norwegian often places it after the noun instead of before it.