صندوق الكرتون هنا.

In Modern Standard Arabic, the verb to be is usually not stated in the present tense.

So Arabic says:

• صندوق الكرتون هنا
• literally: the cardboard box here

but the meaning is The cardboard box is here.

This is called a nominal sentence. In the present tense, Arabic normally leaves out is / am / are.

If you wanted a past or future meaning, then Arabic would use a verb, for example:

• كان صندوق الكرتون هنا = The cardboard box was here
• سيكون صندوق الكرتون هنا = The cardboard box will be here

Because صندوق الكرتون is an iḍāfa construction, often called a construct phrase.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun can make the whole phrase definite

So:

• صندوق الكرتون = literally box of the cardboard / cardboard box
• even though صندوق does not have الـ, the whole phrase is understood as definite because of الكرتون

This is very common in Arabic. Compare:

• باب البيت = the door of the house
• كتاب الطالب = the student’s book

The first noun does not take الـ, but the whole phrase can still be definite.

It is an iḍāfa phrase made of two nouns:

1. صندوق = the first noun
2. الكرتون = the second noun

In traditional grammar:

• صندوق is the muḍāf
• الكرتون is the muḍāf ilayh

The second noun is in the genitive case, and the first noun is linked to it closely.

This structure is often used to show:

• possession: كتاب الطالب = the student’s book
• relationship: باب المدرسة = the school door
• type/material/category: صندوق الكرتون = cardboard box

Because in an iḍāfa, the first noun does not take tanwīn.

So you would not say:

• صندوقٌ الكرتون

Instead, in a fully vowelled form, it would be:

• صندوقُ الكرتونِ هنا

Important rule: the first noun in an iḍāfa normally cannot take:

• الـ
• tanwīn

That is one of the clearest signs that you are looking at an iḍāfa construction.

A careful pronunciation is:

• ṣundūqu l-kartūni hunā

A few notes:

• صندوق = ṣundūq
• الكرتون = al-kartūn
• هنا = hunā

Because ك is a moon letter, the ل in الـ is pronounced clearly:

• al-kartūn
• not ak-kartūn

Also, the last consonant in صندوق is ق, which is a deep q sound, not an English k.

هنا means here.

It is an adverb of place, and in this sentence it tells you where the box is.

So the structure is:

• صندوق الكرتون = the subject/topic
• هنا = the location

Arabic often places words like هنا after the noun phrase, so this word order is very natural.

In fully vowelled MSA, the sentence would normally be:

• صندوقُ الكرتونِ هنا

Here is why:

• صندوقُ is nominative because the whole noun phrase is the subject/topic of the sentence
• الكرتونِ is genitive because it is the second noun in the iḍāfa
• هنا is an adverb and does not take a normal case ending like a regular noun

In everyday writing, these short vowels are usually not written, so you normally just see:

• صندوق الكرتون هنا

Yes. كرتون is a common Arabic word used for cardboard, carton, or sometimes carton material/packaging, depending on context.

So صندوق الكرتون refers to a box connected with cardboard, commonly understood as a cardboard box.

A learner may also see another pattern:

• صندوق من الكرتون = a box made of cardboard

That version more explicitly means made of cardboard.
But the iḍāfa version in your sentence is a normal compact way to express this kind of idea.

Yes, Arabic can change word order for emphasis, but صندوق الكرتون هنا is a very normal and straightforward order.

It works like:

• [the cardboard box] [here]

Putting هنا at the end is natural because the sentence first introduces the thing being talked about, and then gives its location.

Arabic can sometimes move elements around for style or emphasis, but for a learner, this sentence is a good basic pattern to remember.

In an iḍāfa phrase, an adjective usually comes after the whole phrase, not between the two nouns.

For example:

• صندوق الكرتون الكبير هنا = The big cardboard box is here

Notice that الكبير comes after الكرتون, not after صندوق by itself.

That is because the adjective describes the whole noun phrase صندوق الكرتون, not just the first word alone.

So the basic pattern is:

• [iḍāfa phrase] + [adjective]

not:

• صندوق الكبير الكرتون ✘

صندوق is masculine.

That matters when you later use:

• adjectives
• pronouns
• demonstratives

For example:

• هذا صندوق = This is a box
• الصندوق كبير = The box is big

You would use masculine forms with صندوق, not feminine ones.