Söngkonan sagði að hún hefði aldrei séð svona bjartar eldingar áður en hún kom hingað.

Söngkonan means the singer. Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the.

So:

• söngkona = a female singer
• söngkonan = the female singer

The ending -an here is the definite ending for this noun form.

Here að means that and introduces a subordinate clause:

• Söngkonan sagði = The singer said
• að hún hefði... = that she had...

In English, that is often optional, but in Icelandic að is very commonly kept in this kind of sentence.

Hefði séð is the pluperfect subjunctive.

It is made from:

• hefði = subjunctive past of hafa (to have)
• séð = the supine of sjá (to see)

In English, this usually corresponds to had seen.

Because this is reported speech after sagði (said). Icelandic very often uses the subjunctive in subordinate clauses when reporting what someone said, thought, believed, or claimed.

So the sentence is not presented as a direct statement by the narrator, but as something the singer said. That is why hefði is very natural here.

A rough contrast is:

• hafði = more straightforward indicative had
• hefði = subjunctive, often used in indirect/reporting contexts

Áður en means before when it introduces a full clause.

So:

• áður en hún kom hingað = before she came here

This is a fixed expression:

• áður = earlier / before
• en = than / before, in this structure

Together they function as a conjunction meaning before.

Kom is the simple past of koma (to come), and it is used because her coming here is treated as a real completed event.

So:

• áður en hún kom hingað = before she came here

Using hefði komið would change the feel and timing of the sentence and would usually need a different context. In this sentence, the simple past kom is the normal and natural choice.

Not really. Aldrei ... áður is a very natural combination meaning never before.

• aldrei = never
• áður = before / previously

So:

• hafði aldrei séð ... áður = had never seen ... before

English often does the same thing, so the structure is quite parallel.

Svona means something like like this, this kind of, or such. In this sentence, it gives the idea of such bright lightning.

So:

• svona bjartar eldingar = such bright lightning flashes

By contrast, svo usually means so in the sense of degree:

• svo bjartar = so bright

The difference is subtle, but svona fits the idea of lightning of this kind / such bright lightning.

Because the adjective has to agree with the noun in gender, number, and case.

Here:

• eldingar is feminine plural
• bjartar matches it as feminine plural

Also, sjá takes a direct object, so this phrase is in the accusative:

• sjá svona bjartar eldingar = see such bright lightning flashes

For this noun and adjective pattern, the feminine plural nominative and accusative often look the same, so the -ar ending is not surprising.

That is a vocabulary difference between the two languages. Icelandic often uses elding as a countable noun, meaning something like a flash of lightning or bolt of lightning.

So:

• eldingar = lightning flashes / bolts of lightning

English often uses the mass noun lightning, but Icelandic commonly uses the plural count noun in contexts like this.

Because hingað expresses motion toward a place, while hér expresses location.

• hingað = to here
• hér = here

So:

• hún kom hingað = she came here
• hún er hér = she is here

Since the verb is kom (came), Icelandic uses the motion form hingað.

That is the normal Icelandic order in this kind of subordinate clause:

• hún = subject
• hefði = finite verb
• aldrei = adverb
• séð = non-finite verb form

So the pattern is: subject + finite verb + adverb + main verb form

This is very similar to English she had never seen. In a neutral sentence, aldrei naturally comes after the finite verb hefði.