Ez fontos tény.

• ez = this
• fontos = important
• tény = fact

So the sentence means This is an important fact.

Grammatically, ez is the subject, and fontos tény is the predicate noun phrase.

In Hungarian, the verb to be is often left out in the present tense when the subject is third person and the predicate is a noun or an adjective.

So:

• Ez fontos tény. = This is an important fact.
• literally: This important fact.

This is completely normal Hungarian grammar, not an incomplete sentence.

Yes, Ez egy fontos tény. is also possible.

Hungarian often allows the indefinite article egy to be omitted in this kind of predicate structure, especially when the sentence sounds a bit more compact or categorical.

So both are possible:

• Ez fontos tény.
• Ez egy fontos tény.

A rough way to think about it:

• Ez fontos tény. = slightly more compact, matter-of-fact, sometimes more formal or written-sounding
• Ez egy fontos tény. = very natural too, and often closer to how an English speaker expects the sentence to be built

As a learner, if you say Ez egy fontos tény, that is perfectly fine.

Here, ez is a standalone pronoun, meaning this or this thing / this statement.

Compare:

• Ez fontos tény. = This is an important fact.
• ez a tény = this fact

So:

• ez by itself = pronoun
• ez a + noun = demonstrative determiner phrase, like this + noun

In your sentence, there is no noun directly after ez, so it is functioning as this on its own.

In Hungarian, adjectives normally come before the noun they describe.

So:

• fontos tény = important fact
• nagy ház = big house
• érdekes könyv = interesting book

That part is actually quite similar to English.

No. Hungarian adjectives do not agree with nouns the way they do in many Indo-European languages.

That means:

• no grammatical gender
• no adjective endings for masculine/feminine/neuter
• no special singular/plural agreement in this position

So:

• fontos tény = important fact
• fontos tények = important facts

Notice that fontos stays the same. The noun changes, not the adjective.

tény is in the nominative form, which is the basic dictionary form.

That is because it is part of the predicate after an omitted is-type verb, not a direct object.

• tény = nominative, fact
• tényt = accusative, fact as a direct object

So in this sentence, tény is correct:

• Ez fontos tény.

You would use tényt only if fact were the object of a verb, for example in a sentence like I know this fact.

tény is pronounced roughly like tayny, but with Hungarian sounds:

• é is a long vowel, like a long e
• ny is a single consonant sound, similar to the ny in canyon

So tény is approximately:

• tény → tayny

Also remember that in Hungarian, stress normally falls on the first syllable of each word.

Yes, Hungarian word order is more flexible than English, but different orders can change the emphasis.

The neutral order here is:

• Ez fontos tény.

You may also hear:

• Fontos tény ez.

That version puts more emphasis on fontos tény — something like This is an important fact with extra stress on important fact.

So the original sentence is a good neutral model, while changed word order often adds emphasis or style.

It sounds natural and correct, but a little compact.

• Ez fontos tény. can sound somewhat concise, factual, or formal/written.
• Ez egy fontos tény. may sound slightly more everyday and more transparent to beginners.

Both are good Hungarian. If you want the safest learner-friendly version, Ez egy fontos tény. is an easy choice, but the version without egy is absolutely valid too.