Az előzetes információ fontos.

In Hungarian, the verb to be is usually left out in the present tense, third person when one noun or adjective is simply describing another.

So:

Az előzetes információ fontos.
literally looks like
The preliminary information important.

But in normal Hungarian, that already means The preliminary information is important.

You would use an explicit form of to be in other persons, for example:

• Fontos vagyok. = I am important.
• Fontos vagy. = You are important.

And in some other structures, especially for existence or location.

Both a and az mean the in Hungarian.

The choice depends on the sound that follows:

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

Since előzetes begins with the vowel e, Hungarian uses:

az előzetes információ

Compare:

• a fontos adat = the important piece of data
• az előzetes információ = the preliminary information

Előzetes is an adjective modifying információ.

So in:

az előzetes információ

the structure is:

• az = the
• előzetes = adjective, preliminary / prior / advance
• információ = noun, information

Hungarian adjectives usually come before the noun when they directly describe it, just like in English:

• fontos információ = important information
• előzetes információ = preliminary information

Because fontos is not inside the noun phrase here. It is the predicate adjective of the sentence.

There is a difference between:

• fontos információ = important information
  here fontos directly modifies the noun

and

• Az információ fontos. = The information is important.
  here fontos is the main description of the subject

So in your sentence:

• az előzetes információ = the subject
• fontos = what is being said about the subject

That is why it comes after the subject in the neutral word order.

In Hungarian, an adjective used before a noun usually does not agree with the noun in number or case the way adjectives do in many Indo-European languages.

So the adjective stays the same:

• előzetes információ = preliminary information
• előzetes információk = preliminary pieces of information / preliminary information

Notice that előzetes stays előzetes.

This is normal for attributive adjectives in Hungarian.

Yes. Hungarian word order is quite flexible, and changing it often changes the focus or emphasis.

The neutral version is:

Az előzetes információ fontos.

But you could also say:

Fontos az előzetes információ.

This puts more emphasis on fontos — roughly The preliminary information is important / What matters is the preliminary information depending on context.

So both can be correct, but they are not always identical in emphasis.

Információ is in the nominative case, which is the basic dictionary form of the noun.

Hungarian adds endings when a noun has a grammatical role such as:

• object
• location
• direction
• possession-related functions
• and many others

But here információ is simply part of the subject:

Az előzetes információ = The preliminary information

So no extra case ending is needed.

A rough pronunciation guide is:

Az előzetes információ fontos.
awz EH-luh-zeh-tesh een-for-MAH-tsee-oh FON-tosh

A few useful points:

• sz is pronounced like English s
• s is pronounced like English sh
• z is like English z
• ó, á, ő are long vowels
• stress in Hungarian normally falls on the first syllable of each word

So approximately:

• Az → awz
• előzetes → EH-luh-zeh-tesh
• információ → een-for-MAH-tsee-oh
• fontos → FON-tosh

Yes, it is a loanword and looks very familiar to English speakers. It means information.

But you should still remember that Hungarian uses it according to Hungarian grammar:

• it can take Hungarian case endings
• it can take plural forms if needed
• it fits into Hungarian word order

For example:

• információt = information as a direct object
• információk = pieces of information / bits of information

So although the word is familiar, it behaves like a normal Hungarian noun.