A hangoskönyv hosszú.

Because Hungarian often leaves out the verb to be in the 3rd person singular present tense when the predicate is an adjective or a noun.

So:

• A hangoskönyv hosszú. = The audiobook is long.

Hungarian does not need a word like is here.

You do use the verb in other tenses or persons, for example:

• A hangoskönyv hosszú volt. = The audiobook was long.
• A hangoskönyv hosszú lesz. = The audiobook will be long.
• Én fáradt vagyok. = I am tired.

So this missing is is completely normal.

A is the Hungarian definite article, so here it means the.

• a hangoskönyv = the audiobook

Hungarian has two forms of the definite article:

• a before a consonant sound
• az before a vowel sound

Examples:

• a hangoskönyv = the audiobook
• az alma = the apple

Since hangoskönyv begins with h, which is a consonant sound, you use a.

Yes. Hangoskönyv is a single compound noun.

It is made from:

• hangos = sounding, audio, loud
• könyv = book

So Hungarian forms hangoskönyv as one written word, just like English forms audiobook as one word.

This is very common in Hungarian: compounds are often written as a single word.

Because here hosszú is not directly describing the noun inside the noun phrase. It is the predicate adjective: it tells you something about the audiobook.

So:

• A hangoskönyv hosszú. = The audiobook is long.

But if you want the adjective directly before the noun, like in English the long audiobook, then Hungarian does that too:

• a hosszú hangoskönyv = the long audiobook

So the difference is:

• a hosszú hangoskönyv = the long audiobook
• a hangoskönyv hosszú = the audiobook is long

A few useful pronunciation points:

• Hungarian stress usually falls on the first syllable of each word.
• sz sounds like English s in see.
• s sounds like English sh.
• ny sounds like the ny in canyon or like Spanish ñ.
• ö is a rounded vowel, somewhat like German ö or French eu.
• ú is a long u sound.

So:

• hangos has s = sh
• könyv has ny
• hosszú has sz = s, and the final ú is long

A rough pronunciation guide would be:

• A hangoskönyv hosszú ≈ uh HAHN-gosh-könyv HOSS-soo

That is only approximate, but it helps with the main sounds.

Because in Hungarian, sz is treated as a single letter.

So when that sound is doubled, Hungarian writes it as ssz.

That means:

• sz = one s sound
• ssz = a long or doubled s sound

So hosszú is spelled that way because it contains a long sz sound.

This looks strange to English speakers at first, but it is a regular Hungarian spelling pattern.

Not in this sentence.

Hungarian adjectives do not change for gender, because Hungarian has no grammatical gender like he/she nouns in many European languages.

Here:

• hangoskönyv is singular
• hosszú stays in its basic form

If the subject is plural, the predicate adjective often becomes plural too:

• A hangoskönyvek hosszúak. = The audiobooks are long.

But when an adjective comes before a noun, it usually stays unchanged:

• hosszú hangoskönyvek = long audiobooks

So Hungarian agreement works differently from English and from languages like German or French.

Yes, but the emphasis may change.

The neutral sentence is:

• A hangoskönyv hosszú.

You can also say:

• Hosszú a hangoskönyv.

This still means basically The audiobook is long, but now the focus is more on long. It can sound like you are emphasizing or contrasting the length.

Hungarian word order is often about information structure and focus, not just grammar.

So for a simple neutral statement, A hangoskönyv hosszú is the safest pattern.

Usually not in this sentence if you mean the audiobook.

• A hangoskönyv hosszú. = The audiobook is long.

If you say:

• Egy hangoskönyv hosszú.

that means something more like:

• An audiobook is long
• or One audiobook is long

depending on context.

If you leave out the article completely, the result usually sounds unnatural for a normal full sentence like this.

So for this meaning, keep a.

In Hungarian, accent marks are very important. They are not optional.

In this sentence:

• ö in könyv is a different vowel from o
• ú in hosszú shows a long vowel

So u and ú are different sounds, not just different spellings.

This matters because vowel quality and vowel length can change the word. In Hungarian, spelling and pronunciation are closely connected, so you should learn the accents as part of the word itself.