هذا حجر نرد.

In Arabic, the present tense of to be is usually not expressed in simple nominal sentences.

So:

• هذا حجر نرد = This is a die

There is no separate word for is here. Arabic just puts the two parts next to each other:

• هذا = this
• حجر نرد = a die

If you wanted a past or future meaning, then Arabic would use a verb such as كان.

هذا is the demonstrative meaning this for a masculine singular noun.

So the sentence is built as:

• هذا = this
• حجر نرد = a die

Literally, the structure is This, a die; in natural English, that becomes This is a die.

Because حجر is grammatically masculine singular.

Arabic demonstratives agree with the gender and number of the thing being pointed to:

• هذا = this (masculine singular)
• هذه = this (feminine singular)

Since حجر نرد is headed by حجر, which is masculine, هذا is the correct choice.

Literally, حجر means stone, and نرد relates to dice / the game of dice.

So حجر نرد literally means something like:

• a dice stone
• a stone for dice

But idiomatically it means a die.

This is very common in Arabic: a phrase may be built from simple literal parts, but the whole expression has a fixed everyday meaning.

It is two words, but they work together as one noun phrase.

• حجر = stone
• نرد = dice / gaming

Together, they form a fixed expression meaning die.

Grammatically, this is an iḍāfa construction, often called a construct phrase or genitive construction.

An iḍāfa links two nouns together. In English, it often corresponds to:

• X of Y
• or sometimes just a compound noun

Here:

• حجر نرد = literally stone of dice

In an iḍāfa:

1. The first noun does not take ال
2. The first noun does not take tanwīn
3. The second noun is in the genitive case

So in full vocalization, this would be:

• هٰذا حَجَرُ نَرْدٍ

The first noun حجرُ is the main noun of the phrase, and نردٍ comes after it to specify what kind of stone it is.

Because it is the first part of an iḍāfa.

Normally, an indefinite noun like stone might appear as حجرٌ. But in an iḍāfa, the first noun loses tanwīn.

So:

• not حجرٌ نرد
• but حجرُ نردٍ

That is a very important rule of Arabic noun phrases.

With full short vowels, the sentence is:

• هٰذا حَجَرُ نَرْدٍ

Here is why:

• هذا is the subject-like part of the nominal sentence
• حجرُ is the predicate, so it is nominative
• نردٍ is the second term of the iḍāfa, so it is genitive

If you stop at the end of the sentence, Arabic often drops the final short vowel in pronunciation, so you may hear something like:

• hādhā ḥajaru nard

But grammatically, the full form is حَجَرُ نَرْدٍ.

Because the iḍāfa is indefinite here.

In an iḍāfa, the definiteness of the whole phrase depends largely on the second noun:

• حجر نرد = a die / a dice-stone → indefinite
• حجر النرد = the die or the dice-stone → definite

Since نرد here does not have ال, the whole phrase is understood as indefinite.

It is pronounced hādhā.

A rough guide:

• hā = long aa
• dh = like the th in this
• final ā = another long aa

So it sounds approximately like:

• haa-thaa, but with the th of this, not the th of think

Sometimes context may make that possible, but حجر نرد is the clearer expression for a single die.

By itself, نرد can refer more broadly to:

• dice
• the game of dice
• sometimes related gaming meanings

So for a learner, it is safest to understand حجر نرد here as the normal phrase meaning a die.

It is a nominal sentence:

• هذا = the topic / subject-like element
• حجر نرد = the predicate

So the pattern is:

• demonstrative + noun phrase

This is a very common Arabic pattern for identifying something:

• هذا كتاب = This is a book
• هذه سيارة = This is a car
• هذا حجر نرد = This is a die

So the sentence is short, but it shows several important Arabic features at once: demonstratives, nominal sentences, and iḍāfa.