Ez a körülmény különleges.

In Hungarian, when a demonstrative directly modifies a noun, you normally use:

• ez / az = this / that
• plus the definite article a / az
• plus the noun

So:

• ez a körülmény = this circumstance
• az a ház = that house

This is standard Hungarian structure. English uses just one word, but Hungarian usually uses both the demonstrative and the article together.

The definite article has two forms:

• a before a consonant
• az before a vowel

Since körülmény starts with k, which is a consonant, Hungarian uses a:

• ez a körülmény

Compare:

• ez az ember = this person
  because ember starts with a vowel.

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

So:

• Ez a körülmény különleges.
• literally: This circumstance special.
• natural English: This circumstance is special.

This is completely normal Hungarian grammar.

But the verb appears in other situations, for example:

• Ez a körülmény különleges volt. = This circumstance was special.
• Ez a körülmény különleges lesz. = This circumstance will be special.

Körülmény is a noun meaning circumstance, condition, or sometimes factor, depending on context.

A few useful forms:

• körülmény = circumstance
• körülmények = circumstances
• körülményt = circumstance, as a direct object

It is a fairly formal/common word, especially in writing or careful speech.

Különleges is an adjective meaning something like special, unusual, or distinctive, depending on context.

In this sentence it is a predicate adjective:

• Ez a körülmény különleges.
• This circumstance is special.

It can also go before a noun:

• különleges körülmény = a special circumstance

Usually, not when it comes before a noun.

Examples:

• különleges körülmény = special circumstance
• különleges körülmények = special circumstances

Notice that the adjective stays különleges even though the noun becomes plural.

But when an adjective is used as the predicate, it can take plural marking:

• A körülmény különleges. = The circumstance is special.
• A körülmények különlegesek. = The circumstances are special.

So in your sentence, különleges is singular because körülmény is singular.

This order is the most neutral, straightforward way to say it.

• Ez a körülmény = the topic, what we are talking about
• különleges = what we are saying about it

Hungarian word order is flexible, but changes emphasis.

For example:

• Ez a körülmény különleges. = neutral statement
• Különleges ez a körülmény. = stronger emphasis on special

So the sentence you have is the basic, unmarked version.

You add nem before the adjective:

• Ez a körülmény nem különleges.
• This circumstance is not special.

Notice that there is still no separate word for is in the present tense third person.

The simplest way is usually just intonation in speech, or a question mark in writing:

• Ez a körülmény különleges?
• Is this circumstance special?

Hungarian often relies on intonation for yes/no questions, especially in simple sentences like this.

A few helpful pronunciation points:

• Hungarian stress is normally on the first syllable of each word.
• ö and ü are rounded front vowels, somewhat like German ö and ü.
• s in Hungarian is pronounced like English sh.
• ny is pronounced like Spanish ñ or the ny in canyon.

Very roughly:

• Ez = ez
• a = short aw/uh-like vowel
• körülmény = KÖ-rül-mény
• különleges = KÜ-lön-le-gesh

A more accurate pronunciation in IPA is:

• Ez a körülmény különleges.
• /ɛz ɒ ˈkørylmeːɲ ˈkylonlɛɡɛʃ/

No. Hungarian does not have grammatical gender like many European languages do.

So nouns are not masculine, feminine, or neuter, and adjectives do not change for gender.

That means:

• ez
• a
• különleges

do not have to agree with körülmény in gender, because Hungarian simply does not mark that category.

Then Hungarian uses the verb to be.

Examples:

• Ez a körülmény különleges volt. = This circumstance was special.
• Ez a körülmény különleges lesz. = This circumstance will be special.

So the missing is is only a present-tense third-person feature in sentences like this.