Ef fyrirsögnin er áhugaverð, les ég allan textann og skrifa síðan stutta þýðingu.

Ef means if. It introduces a conditional subordinate clause.

So:

• Ef fyrirsögnin er áhugaverð = If the headline is interesting

This clause sets up the condition for what happens next. The rest of the sentence is the main clause: les ég allan textann og skrifa síðan stutta þýðingu.

This is because Icelandic main clauses usually follow a verb-second pattern.

When the sentence begins with something other than the subject — here, the whole Ef-clause — the finite verb comes first in the main clause, and the subject follows it:

• Ef ... , les ég ...

Compare:

• Ég les allan textann. = I read the whole text.
• Ef fyrirsögnin er áhugaverð, les ég allan textann. = If the headline is interesting, I read the whole text.

So the if-clause takes the first slot, then the verb les comes second.

Fyrirsögnin means the headline.

Icelandic usually adds the definite article onto the end of the noun instead of using a separate word like the.

• fyrirsögn = headline
• fyrirsögnin = the headline

So the ending -in here is the definite article attached to the noun.

Because it agrees with fyrirsögnin.

Fyrirsögn is:

• feminine
• singular
• nominative here, because it is the subject of er

Predicate adjectives after er still agree with the subject, so áhugaverð is the feminine singular nominative form meaning interesting.

In other words:

• fyrirsögnin er áhugaverð = the headline is interesting

Because textann is the direct object of les and therefore appears in the accusative.

Here is the breakdown:

• texti = text
• textann = the text in the accusative singular
• allan = all / whole in the masculine accusative singular, agreeing with textann

So:

• allan textann = the whole text / all the text

The form changes because Icelandic marks case on both the noun and the word describing it.

For the same basic reason: this is also a direct object, this time of skrifa, so it is in the accusative.

• þýðing = translation
• þýðingu = accusative singular
• stutta = short in the form that agrees with þýðingu

Since þýðing is feminine singular, the adjective must match it.

So:

• stutta þýðingu = a short translation

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

So:

• þýðing can mean translation or a translation
• stutta þýðingu means a short translation

Icelandic expresses indefiniteness without a separate article. But for definiteness, it usually adds the article to the noun:

• þýðing = a translation / translation
• þýðingin = the translation

Síðan means then, after that, or afterwards.

In this sentence:

• les ég allan textann og skrifa síðan stutta þýðingu
• I read the whole text and then write a short translation

It shows the sequence of actions: first reading, then writing.

Because the same subject, ég, applies to both verbs.

This is normal in Icelandic, just as it is in English:

• I read the whole text and write a short translation

You do not need to repeat ég before skrifa unless you want extra emphasis or a different structure.

So:

• les ég ... og skrifa ... = I read ... and write ...

Because subordinate clauses and main clauses behave differently.

Inside the Ef-clause, Icelandic uses normal subject-verb order:

• fyrirsögnin er áhugaverð

But in the main clause, because the sentence starts with the subordinate clause, Icelandic uses verb-second order:

• les ég

So the contrast is:

• subordinate clause: subject + verb
• main clause after an opening element: verb + subject

That is a very common pattern in Icelandic.

A good rough guide is:

• þ sounds like th in thing
• ð sounds like th in this

So in þýðingu:

• the first sound, þ, is like the th in thin
• the ð is a voiced th sound

This is only an approximation, but it is a very useful one for English speakers.