A vízhatlan zsák a csoporthoz tartozik.

No. In Hungarian, a/az is the definite article, so it means the.

So:

• A vízhatlan zsák = the waterproof bag

If you wanted a waterproof bag, you would normally say:

• Egy vízhatlan zsák

Hungarian uses:

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

That is why this sentence has a vízhatlan zsák and a csoporthoz.

Because there are two definite noun phrases:

• a vízhatlan zsák = the waterproof bag
• a csoporthoz = to the group

Hungarian usually repeats the article for each definite noun phrase, just as English says the bag and the group.

Also, notice that the case ending goes on the noun, not on the article:

• a csoporthoz
• not ahoz csoport

Vízhatlan means waterproof or watertight.

It is an adjective, and in Hungarian, adjectives normally come before the noun, just as in English:

• vízhatlan zsák = waterproof bag

So the structure is very familiar to an English speaker here.

A useful extra note: Hungarian adjectives do not change for gender, and in this position they also do not take a plural ending:

• vízhatlan zsák = waterproof bag
• vízhatlan zsákok = waterproof bags

Not vízhatlanok zsákok.

Because Hungarian adds a case suffix to the noun.

Here the suffix is -hoz, which is one form of -hoz / -hez / -höz. This ending often means to or toward.

So:

• csoport = group
• csoporthoz = to the group

With the verb tartozik, this combination means belongs to.

So:

• a csoporthoz tartozik = belongs to the group

The form -hoz is used here because csoport has back vowels, so this is a case of vowel harmony.

Because tartozik uses this pattern idiomatically.

In Hungarian, you say:

• valamihez tartozik = belongs to something

So even though -hoz/-hez/-höz often literally means to/toward, with tartozik it is the normal way to express belonging.

For example:

• A könyv a könyvtárhoz tartozik. = The book belongs to the library.
• Ez a név a listához tartozik. = This name belongs on the list / belongs to the list.

This is just something you learn with the verb: tartozik + -hoz/-hez/-höz.

Here tartozik means belongs, is connected with, or is part of.

It is the 3rd person singular form of tartozni.

So:

• A vízhatlan zsák a csoporthoz tartozik.
• The waterproof bag belongs to the group.

A very important point: tartozik can also mean owes, but in a different structure.

For example:

• Péter pénzzel tartozik. = Peter owes money.

So the meaning depends a lot on the pattern around it. In your sentence, because of a csoporthoz, the meaning is clearly belongs to.

This is a natural, neutral Hungarian word order.

The sentence starts with the topic:

• A vízhatlan zsák = as for the waterproof bag...

Then it says something about it:

• a csoporthoz tartozik = it belongs to the group

Hungarian word order is flexible, but it is not random. It often shows topic and focus.

This version sounds like a neutral statement about the bag.

If you changed the order, the emphasis could change. For example:

• A csoporthoz tartozik a vízhatlan zsák.

This can put more attention on the group as the relevant destination or category.

No. Hungarian has no grammatical gender like many Indo-European languages do.

That means:

• zsák is not masculine, feminine, or neuter
• csoport is not masculine, feminine, or neuter
• vízhatlan does not change for gender
• a does not change for gender either

This is often good news for English speakers: you do not have to memorize noun genders.

You would make both the noun and the verb plural:

• A vízhatlan zsákok a csoporthoz tartoznak.
• The waterproof bags belong to the group.

Changes:

• zsák → zsákok = bags
• tartozik → tartoznak = belong

The adjective stays the same:

• vízhatlan zsák
• vízhatlan zsákok

You add nem before the part you want to negate.

The simplest negative version is:

• A vízhatlan zsák nem a csoporthoz tartozik.
• The waterproof bag does not belong to the group.

In speech, where you place nem can slightly affect emphasis, but this version is a good standard pattern for learners.

Two sounds here are especially useful for English speakers:

• zs sounds like the s in measure
• cs sounds like the ch in chair

So:

• zsák starts with a zh-like sound
• csoporthoz starts with a ch-like sound

Also, Hungarian long vowels matter:

• í in vízhatlan is long
• á in zsák is long

So vowel length is part of correct pronunciation, not just spelling decoration.