هذا الحائط قديم.

In Arabic, the normal order is:

• demonstrative + noun
• so: هذا الحائط = this wall

That is different from English only in form, not meaning. Arabic puts this/that directly before the noun it points to.

Arabic usually leaves out the verb to be in the present tense.

So:

• هذا الحائط قديم literally looks like this wall old
• but it means This wall is old

This is completely normal in Arabic.
If you wanted was, will be, etc., Arabic would use a verb, but in the present tense it is usually omitted.

Because the sentence means this wall, referring to a specific wall.

In Arabic, after a demonstrative like هذا, the noun is normally definite:

• هذا الحائط = this wall
• not usually this a wall

So الـ is expected here.

Because قديم is the predicate adjective in the sentence: it tells us something about the wall.

In Arabic nominal sentences like this, the pattern is often:

• definite subject/topic + indefinite predicate

So:

• هذا الحائط = the topic, this wall
• قديم = the description, old

If you said هذا الحائط القديم, that would usually mean this old wall, where old is directly modifying wall, not serving as the main predicate of the sentence.

So the difference is:

• هذا الحائط قديم = This wall is old
• هذا الحائط القديم = this old wall

Because الحائط is a masculine noun in Arabic.

• هذا is used with masculine singular nouns
• هذه is used with feminine singular nouns

So:

• هذا الحائط = this wall
• not هذه الحائط

Even though in English objects do not usually have grammatical gender, Arabic nouns do.

Yes. Adjectives and predicate adjectives in Arabic must agree with the noun they describe in:

• gender
• number

Since الحائط is:

• singular
• masculine

the adjective is also:

• singular
• masculine → قديم

If the noun were feminine singular, you would expect قديمة instead.

This is a nominal sentence: a sentence built around a noun phrase rather than starting with a verb.

Its two main parts are:

• هذا الحائط = the topic / subject-like part
• قديم = the predicate / comment

So the sentence structure is essentially:

• This wall
  • old
• meaning This wall is old

هذا is pronounced approximately hādhā.

A few points:

• the هـ gives an h sound
• ذ sounds like the th in this
• the final ا gives a long aa sound

So it is roughly:

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

It is pronounced approximately al-ḥāʾiṭ.

Important parts:

• ال = al-
• ح is a deeper, breathier h sound than English h
• ائ includes a hamza (ء), a brief glottal stop
• ط is an emphatic t

A rough learner-friendly pronunciation is:

• al-haa-it

  but that does not fully capture the special sounds ḥ, ʾ, and ṭ.

That comes from the hamza: ء.

In الحائط, the sequence ائ includes a hamza, so the word is not pronounced as one completely smooth syllable. There is a slight break or catch in the voice:

• ḥāʾiṭ

English speakers often miss this sound at first, but it is a real consonant in Arabic.

Yes, in fully vocalized formal Arabic, case endings are possible here.

You could write it as:

• هٰذا الحائطُ قديمٌ

Here:

• الحائطُ is nominative
• قديمٌ is also nominative

But in normal everyday writing, these short vowel endings are usually omitted, so learners commonly see:

• هذا الحائط قديم

without the final vowel marks.

Yes, but the meaning shifts slightly.

• هذا الحائط قديم = This wall is old
• هذا جدار قديم = usually This is an old wall

Why? Because in هذا جدار قديم, the noun جدار is indefinite, and قديم directly describes it.

So the original sentence is about a specific wall already identified, while هذا جدار قديم presents something as an old wall.

No. Another very common word is جدار.

Both can mean wall, though usage can vary by region and context.

In Modern Standard Arabic:

• حائط
• جدار

are both understood. A learner may encounter both, so it is useful to recognize them.

Arabic has no separate word for a/an.

Instead:

• indefinite nouns usually appear without الـ
• definite nouns usually take الـ

So:

• حائط = a wall
• الحائط = the wall

In this sentence, the noun is definite because it is this wall, a specific wall.

No. هذا means this.

For that (masculine singular), Arabic normally uses:

• ذلك الحائط قديم = That wall is old

So:

• هذا = this
• ذلك = that

The distinction matters in Arabic just as it does in English.