A nyelvi kérdés fontos.

A is the Hungarian definite article, equivalent to the in English.

So:

• a kérdés = the question
• a nyelvi kérdés = the linguistic/language-related question

Hungarian has two forms of the definite article:

• a before consonant sounds
• az before vowel sounds

Here nyelvi starts with a consonant sound, so it is a.

Nyelv is the noun language (or tongue).

To turn it into an adjective meaning linguistic or language-related, Hungarian adds -i:

• nyelv = language
• nyelvi = linguistic, language-related

So nyelvi kérdés means something like:

• language question
• linguistic question
• question related to language

This -i ending is very common in Hungarian for making adjectives from nouns.

Kérdés literally means question, but depending on context it can also mean issue or matter.

So nyelvi kérdés could mean:

• a question about language
• a linguistic issue
• a language-related matter

In real usage, Hungarian often uses kérdés a bit more broadly than English question.

Here fontos means important, and it is the predicate of the sentence:

• A nyelvi kérdés = the language-related question
• fontos = is important

Hungarian often places the descriptive part of this kind of sentence after the subject, just like English:

• A ház nagy. = The house is big.
• A kérdés fontos. = The question is important.

So fontos comes at the end because it is what is being said about the subject.

Hungarian usually leaves out is in the third person singular present tense.

So instead of saying a separate word for is, Hungarian simply says:

• A nyelvi kérdés fontos. = The language question is important.

This is very normal in Hungarian.

Compare:

• Én fáradt vagyok. = I am tired.
• Te fáradt vagy. = You are tired.
• Ő fáradt. = He/she is tired. ← no separate word for is

So the sentence is complete even though there is no visible verb.

In Hungarian, adjectives generally do not agree with the noun in gender, and Hungarian has no grammatical gender anyway.

Also, in this sentence fontos is a predicate adjective, and it stays unchanged:

• A kérdés fontos.
• A kérdések fontosak. = The questions are important.

Only in the plural predicate form do you see plural marking on the adjective:

• singular: fontos
• plural: fontosak

But there is no masculine/feminine/neuter agreement like in many Indo-European languages.

Yes. In nyelvi kérdés, nyelvi is an attributive adjective modifying kérdés.

Hungarian adjectives usually come before the noun when they directly describe it:

• nagy ház = big house
• fontos kérdés = important question
• nyelvi kérdés = linguistic question

So inside the noun phrase, the order is:

• a
  • adjective
    • noun
• a nyelvi kérdés

Yes, Hungarian word order is more flexible than English, but changes in word order often affect focus or emphasis.

The neutral version is:

• A nyelvi kérdés fontos.

If you move things around, you may create a different emphasis. For example:

• Fontos a nyelvi kérdés. = The language question is important.
  This puts more emphasis on important.

So the original sentence is the most straightforward, neutral way to say it.

A rough pronunciation guide:

• A = short aw
• nyelvi ≈ nyel-vee
• kérdés ≈ kayr-daysh
• fontos ≈ fon-tosh

A few useful notes:

• ny is like the ny in Spanish señor or the n in canyon
• é is a long ay sound
• s in Hungarian sounds like English sh
• sz is the normal English s

So kérdés ends with a sh sound because of the final s.

No, not as written.

That would be:

• A nyelv fontos. = The language is important.

Your sentence is:

• A nyelvi kérdés fontos.

Because kérdés is present, the subject is the language-related question/issue, not the language itself.

It can be either, depending on context.

• linguistic question sounds more natural in academic or formal English
• language question can work in broader or more political/social contexts
• sometimes language-related issue is the best translation

So nyelvi is quite broad: it means connected with language, not necessarily only with linguistics as a field.

The structure is:

• A nyelvi kérdés = subject noun phrase
• fontos = predicate adjective

So the pattern is:

• [Definite article] + [adjective] + [noun] + [predicate adjective]

In a gloss-like breakdown:

• A = the
• nyelv-i = language-ADJ
• kérdés = question/issue
• fontos = important

That makes the full sentence a very typical Hungarian X is Y sentence without an expressed is.