Lokaorðin eru of stutt, svo hún ætlar að skrifa betri niðurstöðu á morgun.

Lokaorðin is a compound noun. Icelandic, like English, often builds new words by joining smaller words together.

• loka- = closing, final
• orð = word

So lokaorð means closing word(s) or final remark(s), and lokaorðin means the closing words. Writing it as one word is completely normal in Icelandic compounds.

Because Icelandic usually puts the definite article at the end of the noun instead of using a separate word.

So:

• lokaorð = closing words / a closing word
• lokaorðin = the closing words

The ending -in here is the definite article.

Because lokaorðin is plural, so the verb must also be plural.

The verb vera = to be has:

• er = is
• eru = are

So:

• lokaorðið er = the closing word is
• lokaorðin eru = the closing words are

Adjectives in Icelandic agree with the noun in gender and number.

Here, lokaorðin is neuter plural, so the adjective must also be in the neuter plural form:

• masculine plural: stuttir
• feminine plural: stuttar
• neuter plural: stutt

That is why the sentence has of stutt.

Here of means too, in the sense of more than is good or acceptable.

So:

• of stutt = too short
• mjög stutt = very short

This is an important difference. Of is not just emphasis; it suggests a problem.

Here svo means so or therefore. It connects the first idea to the result:

• The closing words are too short,
• so she is going to write a better conclusion tomorrow.

In other contexts, svo can also mean things like then, like that, or so much, but here it clearly means so/therefore.

This is a very common Icelandic pattern:

• ætla að + infinitive

It means intend to, plan to, or often be going to.

So:

• hún ætlar að skrifa = she intends to write / she is going to write

Icelandic does not use a separate future tense the way English often does. Very often, future meaning is expressed with the present tense plus context, or with verbs like ætla.

Because að is the infinitive marker, similar to English to.

So:

• skrifa = write
• að skrifa = to write

After ætla, Icelandic normally uses að + infinitive:

• ætla að fara = intend to go
• ætla að skrifa = intend to write

Because Icelandic does not have an indefinite article like English a/an.

A bare noun can often mean a or an depending on context.

So:

• niðurstaða can mean a conclusion
• niðurstaðan means the conclusion

That is why betri niðurstöðu can mean a better conclusion without any separate word for a.

There are two things happening here:

1. Betri is the comparative of góður

   • góður = good
   • betri = better

2. Niðurstaða changes form because it is the direct object of skrifa
   The noun niðurstaða is feminine, and here it appears in the accusative singular:

   • nominative: niðurstaða
   • accusative: niðurstöðu

So skrifa betri niðurstöðu means write a better conclusion.

Comparative adjectives in Icelandic have fewer visible endings than many basic adjectives, so betri often stays the same across several forms.

Here it matches niðurstöðu, but the comparative form is still betri.
If the noun were neuter singular, you would often see betra instead:

• betri niðurstöðu = a better conclusion
• betra svar = a better answer

Á morgun is a fixed expression meaning tomorrow.

Even though á often means on, it is best to learn á morgun as a whole phrase rather than translating it word for word.

So:

• á morgun = tomorrow

It does not specifically mean in the morning here.

Because this clause begins with the subject hún, so the normal order is:

• hún ætlar = she intends

Icelandic often follows verb-second patterns, but the important idea is that the finite verb tends to come early in the clause. If another element is moved to the front, the order changes:

• Hún ætlar að skrifa á morgun.
• Á morgun ætlar hún að skrifa.

Both are possible, but in your sentence the subject comes first, so hún ætlar is the natural order.