Solnedgången var faktiskt fantastisk.

Because Swedish usually puts the definite article at the end of the noun.

• solnedgång = sunset
• solnedgången = the sunset

So -en here means the.

It is a compound noun:

• sol = sun
• nedgång = going down / descent

So solnedgång literally means something like sun-down-going, which is the normal Swedish word for sunset.

Compound nouns are very common in Swedish.

Because var is the past tense of är.

• är = is
• var = was

So:

• Solnedgången är fantastisk = The sunset is fantastic
• Solnedgången var fantastisk = The sunset was fantastic

Faktiskt usually means actually, in fact, or sometimes really, depending on context.

In this sentence, it adds emphasis and can suggest a mild sense of surprise:

• Solnedgången var fantastisk = The sunset was fantastic
• Solnedgången var faktiskt fantastisk = The sunset was actually fantastic

It does not always sound corrective in Swedish as strongly as actually sometimes does in English. Often it just adds emphasis.

Because Swedish sentence adverbs often come after the finite verb in a main clause.

Here:

• Solnedgången = subject
• var = finite verb
• faktiskt = sentence adverb
• fantastisk = adjective

So the normal word order is:

Subject + verb + sentence adverb + complement

That is why var faktiskt sounds natural.

Because fantastisk agrees with solnedgången, and solnedgång is an en-word.

For singular en-words, the adjective in this kind of sentence usually stays in its basic form:

• en solnedgång
• Solnedgången var fantastisk

You would often see -t with an ett-word:

• ett hus
• Huset var fantastiskt

Yes, very much so. It usually means fantastic, great, or wonderful.

So fantastisk is a very natural word here. It is not unusually strong or strange.

Because Swedish capitalization rules are similar to English in this way: normally only the first word of the sentence and proper nouns are capitalized.

So:

• Solnedgången var faktiskt fantastisk.

Only Solnedgången has a capital letter because it begins the sentence.

Roughly: SOHL-ned-gong-en

A few helpful points:

• sol sounds roughly like sool with a clear l
• ned has a long e sound, somewhat like nayd but not exactly
• gång has the Swedish å, similar to the vowel in British song for many learners
• -en at the end is the definite ending

In compounds, the main stress usually falls on the first part, so SOL gets the strongest stress.

Yes. That would also be natural.

• faktiskt = actually / in fact
• verkligen = really / truly

The nuance is a little different:

• faktiskt can suggest surprisingly or contrary to expectation
• verkligen is more straightforward emphasis

So both work, but they do not feel exactly the same.

Yes. It is very typical and natural.

It follows a common pattern:

Subject + past tense of verb + adverb + adjective

• Solnedgången = subject
• var = verb
• faktiskt = adverb
• fantastisk = adjective

So this is a very good example of standard everyday Swedish word order.