Hennes rubrik är tydlig, men mitt original behöver ändras.

Hennes means her and is a non-reflexive possessive.

Swedish uses sin / sitt / sina when the owner is the same as the subject of the clause:

• Hon ändrar sin rubrik. = She changes her own heading.

But hennes points to a female owner without that reflexive meaning:

• Jag läser hennes rubrik. = I’m reading her heading.

In Hennes rubrik är tydlig, hennes is simply the normal word for her.

Because original is an ett-word in Swedish:

• ett original

Possessives match the grammatical gender of the noun:

• min for en-words
• mitt for ett-words
• mina for plural

So:

• min rubrik because rubrik is an en-word
• mitt original because original is an ett-word

Because the adjective agrees with rubrik, and rubrik is an en-word.

With predicate adjectives after är, Swedish still shows agreement:

• en rubrik → tydlig
• ett original → tydligt
• plural → tydliga

So:

• Rubriken är tydlig
• Originalet är tydligt

That is why the sentence says Hennes rubrik är tydlig.

In Swedish, a possessive usually takes the article’s place.

So you say:

• hennes rubrik
• mitt original

not:

• en hennes rubrik
• ett mitt original

This is similar to English, where you say her heading, not the her heading.

Yes. Here original is a noun.

In Swedish, ett original can mean something like:

• the original version
• the original text
• the original copy
• the source document

So mitt original means my original in the sense of an original document/text/version, not my original as an adjective.

Because behöva is normally followed by an infinitive without att.

Examples:

• Jag behöver läsa.
• Vi behöver gå.
• Det behöver ändras.

So behöver ändras is completely normal Swedish.

It is made up of:

• behöver = present tense of behöva (need)
• ändras = passive infinitive of ändra (to be changed)

Together, behöver ändras means:

• needs to be changed
• or more naturally in English, needs changing

So the structure is basically:

• [subject] + behöver + passive infinitive

Ändras is an -s passive form of ändra.

Swedish often forms the passive by adding -s:

• ändra = change
• ändras = be changed

This is very common in Swedish and is often more compact than using a separate word like bli.

Compare:

• Originalet behöver ändras.
• Originalet behöver bli ändrat.

The first one is usually the more natural choice here.

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

In this clause:

• mitt original = first position
• behöver = finite verb, second position
• ändras = infinitive later in the clause

After men, you start a new main clause, and that clause also follows normal Swedish main-clause word order:

• Hennes rubrik är tydlig, men mitt original behöver ändras.