A speciális dobókocka piros.

It means the.

In Hungarian, the definite article is a or az:

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

So:

• a speciális dobókocka = the special die
• az alma = the apple

If you want a/an in Hungarian, that is usually egy.

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

So:

• A speciális dobókocka piros. = The special die is red.

Hungarian does not need van here.

But compare:

• Én piros vagyok. = I am red.
• A dobókocka az asztalon van. = The die is on the table.

So the missing is is completely normal in this sentence.

They are doing different jobs.

• speciális dobókocka = special die
  Here speciális directly modifies the noun, so it goes before the noun.

• A speciális dobókocka piros. = The special die is red.
  Here piros is the predicate adjective, so it comes after the subject phrase.

Compare:

• a piros dobókocka = the red die
• A dobókocka piros. = The die is red

Yes, it is one compound word.

It is made from:

• dobó = throwing / something used for throwing
• kocka = cube

So dobókocka literally means something like throwing cube, which is the normal Hungarian word for die.

It is singular here. The plural is:

• dobókockák = dice

Unlike English, Hungarian does not have an irregular die/dice pair here.

Not in this sentence.

Hungarian adjectives before nouns usually do not change for:

• gender, because Hungarian has no grammatical gender
• number
• definiteness

So you get:

• a speciális dobókocka = the special die
• a speciális dobókockák = the special dice

Notice that speciális stays the same.

A useful extra point: when an adjective is used as the predicate with a plural subject, it often does take a plural ending:

• A dobókockák pirosak. = The dice are red.

You could say that, but it changes the emphasis.

The given sentence:

• A speciális dobókocka piros.

is a neutral way to say The special die is red.

If you say:

• Piros a speciális dobókocka.

then piros gets stronger focus, as if you are emphasizing red.

Hungarian word order is often about topic and focus, not just subject-verb-object patterns like in English.

The accents are an important part of Hungarian spelling and pronunciation.

For example:

• á
• ó

These are not optional marks. They show different vowel sounds, and often vowel length too.

So:

• a and á are different vowels
• o and ó are different vowels

You should learn the accented forms as part of the word itself:

• speciális
• dobókocka

A rough pronunciation guide is:

• A ≈ aw
• speciális ≈ SHPE-tsi-aa-lish
• dobókocka ≈ DO-boh-kots-kaw
• piros ≈ PEE-rosh

A few very useful pronunciation points:

• Hungarian words are usually stressed on the first syllable
• s is pronounced like English sh
• c is pronounced like ts

So:

• speciális starts with a sh sound, not an English s
• piros ends with sh, not s

Hungarian and English do not always use articles in exactly the same way.

In this sentence, A speciális dobókocka refers to a specific, identifiable die, so Hungarian uses the definite article a.

That is why the sentence means:

• The special die is red

If you wanted a more indefinite idea, Hungarian would usually use egy:

• Egy speciális dobókocka piros. = A special die is red.

But that sounds less natural unless the context really calls for an indefinite subject.

Yes, Hungarian also has vörös, and both words can mean red, but piros is the normal everyday choice for the color of ordinary objects.

So for a die, piros is the most natural word:

• A speciális dobókocka piros.

vörös is also used, but often in more specific contexts, for example:

• darker or deeper red shades
• fixed expressions
• hair, wine, political or historical terms in some cases

For a basic color sentence like this one, piros is the best default word.