A tápkábel a dobozban van.

It is the definite article, equivalent to the in English.

So:

• a tápkábel = the power cable

Hungarian has two forms of the definite article:

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

Since tápkábel starts with t, Hungarian uses a.

That second a also means the.

Hungarian normally keeps the article even when the noun has a case ending:

• a doboz = the box
• a dobozban = in the box

So the article is not replaced by the ending; you use both:

• a
  • doboz
    • -ban

-ban is a case ending meaning in.

So:

• doboz = box
• dobozban = in a/the box

Hungarian often expresses meanings like in, on, to, from, etc. with endings attached directly to the noun instead of separate prepositions.

Here, English uses two words:

• in the box

Hungarian uses:

• a dobozban

This is because of vowel harmony, a very important Hungarian pattern.

The ending has two common forms:

• -ban
• -ben

Words with mostly back vowels usually take -ban.
Words with mostly front vowels usually take -ben.

Since doboz contains back vowels, it becomes:

• dobozban

Compare:

• házban = in the house
• kertben = in the garden

Van means is.

In this sentence:

• A tápkábel a dobozban van.
• The power cable is in the box.

It is the 3rd person singular present form of lenni, the verb to be.

That is a very common question, and yes, Hungarian often omits the verb to be in the present tense — but not always.

For example:

• A tápkábel fekete. = The power cable is black.
  • No van

But with location, Hungarian normally does use van:

• A tápkábel a dobozban van. = The power cable is in the box.

So a good beginner rule is:

• identity/description in present tense → often no van
• location/existence → usually van

Yes, tápkábel is one word, and it is a compound noun, which is very common in Hungarian.

It is made from:

• táp = power supply / feed / power
• kábel = cable

So tápkábel literally means something like power cable or power-supply cable.

Hungarian often combines nouns into one word where English may use two separate words.

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

This sentence is a normal, neutral way to say:

• The power cable is in the box.

Structure:

• A tápkábel = topic, what we are talking about
• a dobozban van = what we say about it

Other orders are possible, but they may sound more marked or emphasize something different. For example:

• A dobozban van a tápkábel.
  = The cable is in the box / In the box is the power cable.

That version puts more attention on the box or answers a question like Where is the power cable?

So the sentence you have is a very natural neutral order.

Because dobozban begins with a consonant sound.

Hungarian definite article:

• a before consonants
• az before vowels

So:

• a dobozban
• but az autóban = in the car

Even though the noun has an ending, the choice still depends on the sound at the beginning of the whole noun form.

You would use -ba / -be instead of -ban / -ben.

So:

• a dobozban = in the box
  
  • location, already inside
• a dobozba = into the box
  
  • movement toward the inside

Compare:

• A tápkábel a dobozban van. = The power cable is in the box.
• A tápkábelt a dobozba teszem. = I put the power cable into the box.

This is an important Hungarian distinction:

• -ban/-ben = inside, static location
• -ba/-be = into, movement

A simple approximate pronunciation is:

• aw TAAP-kaa-bel aw DO-boz-bon von

A more careful breakdown:

• A sounds roughly like the o in British hot
• táp has a long á, so it is held longer: taap
• kábel = kaa-bel
• dobozban = do-boz-bon
• van = von with a Hungarian a

A rough IPA version is:

• [ɒ ˈtaːpkaːbɛl ɒ ˈdobozbɒn vɒn]

The long á is important: it is longer than a short a.

You can keep the same words and use question intonation in speech:

• A tápkábel a dobozban van?
• Is the power cable in the box?

In writing, Hungarian uses the normal question mark just like English.

So often the difference between statement and yes/no question is mainly intonation and punctuation, not a change in word order.

You use nincs, which is the negative form used here.

• A tápkábel nincs a dobozban.
• The power cable is not in the box.

Notice that in Hungarian the negative form often changes more than just adding a separate word like not.

Compare:

• van = is
• nincs = is not / there is not

So Hungarian does not usually say nem van here. It uses nincs instead.