Hlustunaræfingin fær hana til að heyra sérhljóðin betur, en samhljóðin eru samt erfið.

Because Icelandic, like the other Germanic languages in the North, very often makes compound nouns as a single word.

Hlustunaræfingin can be broken down like this:

• hlustunar- = of listening / listening-
• æfing = exercise
• -in = the

So hlustunaræfingin literally looks like the listening exercise.

It is the suffixed definite article, which is very common in Icelandic.

So:

• æfing = exercise
• æfingin = the exercise

Instead of putting a separate word like English the in front, Icelandic often attaches the article to the end of the noun.

Because hana is the accusative form of she/her, while hún is the nominative form.

Here hana is the object of fær:

• hún = she
• hana = her

So the sentence uses hana because the exercise is affecting her.

This is a very useful Icelandic pattern:

fá einhvern til að + infinitive

It means to get/make someone to do something.

So here:

• fær = gets / makes
• hana = her
• til að heyra = to hear

Together, fær hana til að heyra means makes her hear or gets her to hear.

In this construction, til að introduces the infinitive.

With fá einhvern til að gera eitthvað, the til að is part of the normal pattern. So you learn it as a chunk:

• fá hana til að heyra
• fá mig til að skilja
• fá þau til að hlæja

In many contexts til að can also mean in order to, but here it is specifically part of the fá ... til að ... structure.

That ending shows the definite article again, here in the plural.

So:

• sérhljóð = a vowel / vowels

• sérhljóðin = the vowels

• samhljóð = a consonant / consonants
• samhljóðin = the consonants

The sentence is talking about the vowel sounds and consonant sounds as a known set, so the definite form makes sense.

They are in different cases because they have different jobs in the sentence.

• sérhljóðin is the object of heyra, so it is accusative plural
• samhljóðin is the subject of eru, so it is nominative plural

However, these forms look the same here. That is normal for many neuter plural nouns in Icelandic: nominative and accusative often have the same form.

Because betur is the comparative adverb meaning better.

It comes from:

• vel = well
• betur = better
• best = best

Since it describes the verb heyra (to hear), Icelandic uses the adverb:

• heyra betur = hear better

It is not describing a noun, so an adjective form would not be right here.

It can mean either, depending on context.

In this sentence, en means but, because it connects two contrasting clauses:

• the listening exercise helps with the vowels
• but the consonants are still difficult

In other sentences, en can also mean than, as in comparisons.

Samt means something like still, nevertheless, or all the same.

It adds a contrast:

• the exercise helps with the vowels,
• but the consonants are still difficult.

So samt emphasizes that the difficulty remains despite the improvement.

Because it agrees with samhljóðin, which is neuter plural.

The adjective is from erfiður = difficult. Its neuter plural form is erfið.

So:

• samhljóðin = the consonants
• eru erfið = are difficult

Also, after vera (to be), predicate adjectives are usually not made definite just because the noun is definite. So samhljóðin eru erfið is normal Icelandic for the consonants are difficult.

Because Icelandic normally follows a verb-second pattern in main clauses.

In the second clause:

• first comes samhljóðin
• second comes the finite verb eru
• then comes samt
• then the adjective erfið

So the neutral order is:

samhljóðin eru samt erfið

This is a very typical Icelandic sentence pattern.