Az úszómedence nagy.

Hungarian has two forms of the definite article: a and az.

• Use az before a word that begins with a vowel sound.
• Use a before a word that begins with a consonant sound.

Since úszómedence starts with ú, the correct article is az:

• az úszómedence
• but a medence

It works a bit like choosing a or an in English, though here it is for the, not for the indefinite article.

Because Hungarian very often writes compound nouns as a single word.

Here:

• úszó = swimming
• medence = pool / basin

Together, úszómedence means swimming pool.

This is very common in Hungarian. English often uses two words where Hungarian prefers one compound word.

Because in this sentence nagy is not directly describing the noun inside a noun phrase; it is the predicate of the sentence.

Compare:

• nagy úszómedence = a big swimming pool
  
  • here nagy comes before the noun
• Az úszómedence nagy. = The swimming pool is big.
  
  • here nagy comes after the noun because it is the predicate

So Hungarian behaves much like English here in terms of sentence structure: The swimming pool is big.

In Hungarian, the present-tense 3rd person form of to be is often omitted when the predicate is a noun or an adjective.

So instead of saying something equivalent to Az úszómedence van nagy, Hungarian simply says:

• Az úszómedence nagy.

This is completely normal.

A useful comparison:

• A ház nagy. = The house is big.
• A fiú tanár. = The boy is a teacher.

But van does appear in other situations, for example with location:

• Az úszómedence a kertben van. = The swimming pool is in the garden.

No. It is related, but it is not the same thing.

• nagy úszómedence = a big swimming pool
  
  • this is just a noun phrase, not a full sentence
• Az úszómedence nagy. = The swimming pool is big.
  
  • this is a complete sentence

So if you want to name an object, you can say nagy úszómedence.
If you want to make a statement about it, you say Az úszómedence nagy.

Because az marks the noun as definite: the swimming pool, not just a swimming pool.

Hungarian uses the definite article very often when referring to a specific thing already known from the context.

So:

• Az úszómedence nagy. = The swimming pool is big.
• Egy úszómedence nagy. would mean A swimming pool is big, which sounds more general or less natural in many contexts.

In normal speech, if both speaker and listener know which pool is meant, the definite article is the natural choice.

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

That means:

• nouns are not masculine, feminine, or neuter
• adjectives do not change for gender

So nagy stays nagy regardless of whether you are talking about something that would be he, she, or it in English.

That is one thing English speakers often find pleasantly simple about Hungarian.

A few helpful points:

• Hungarian stress is usually on the first syllable of the word.
• ú and ó are long vowels.
• sz is pronounced like English s.
• plain Hungarian s is pronounced like English sh.
• gy is a special Hungarian sound, often approximated by English speakers as a soft dy sound.

Very roughly:

• úszómedence ≈ OO-soh-meh-den-tseh
• nagy ≈ something like nody / nawdy, with a soft final consonant

These are only rough guides, but they help avoid some common mistakes, especially with sz and gy.

Yes, Hungarian word order is flexible, and changing it can change the emphasis.

The neutral sentence is:

• Az úszómedence nagy.

But you could also say:

• Nagy az úszómedence.

This puts more emphasis on nagy, something like:

• The swimming pool is big
• or even Big is the swimming pool, in a slightly marked sense

So the original version is the most straightforward, neutral order for a learner to use first.