الذهب جميل.

In Arabic, the present-tense verb to be is usually not stated in simple sentences like this.

So:

• الذهب جميل = Gold is beautiful

This is called a nominal sentence in Arabic.
If you wanted was or will be, Arabic would normally use an actual verb, but in the present tense it is usually left out.

الـ is the Arabic definite article, equivalent to the in English.

So:

• ذهب = gold / golden substance (indefinite, depending on context)
• الذهب = the gold, or more naturally in many contexts, gold as a known substance or category

In Arabic, generic statements often use the definite article where English may not. So الذهب جميل can naturally mean Gold is beautiful.

Because جميل is the predicate of the sentence, not another definite noun.

In a basic Arabic sentence like this:

• الذهب = the subject
• جميل = the description/predicate

Arabic often uses this pattern:

• definite noun + indefinite adjective/predicate

So الذهب جميل literally has the structure:

• the gold + beautiful

That is the normal way to say The gold is beautiful or Gold is beautiful.

If you said الذهب الجميل, that would usually mean the beautiful gold, not gold is beautiful.

Because جميل here is not really an attributive adjective like in beautiful gold. It is the predicate: it tells you something about the subject.

Compare:

• الذهب جميل = Gold is beautiful
• الذهب الجميل = the beautiful gold

So in الذهب جميل, the second word comes after the noun because Arabic is making a full statement, not just a noun phrase.

In careful pronunciation, الـ changes slightly here because ذ is a sun letter.

So الذهب is pronounced approximately:

• adh-dhahab(u)

What happens is:

• the ل of الـ is not pronounced
• the following ذ is strengthened

So although it is written الذهب, it is pronounced more like adh-dhahab.

In fully vocalized, careful Modern Standard Arabic, this sentence is:

• الذَّهَبُ جَمِيلٌ

That gives:

• الذَّهَبُ = adh-dhahabu
• جَمِيلٌ = jamīlun

These endings show nominative case, because both the subject and the predicate of this kind of sentence are nominative.

In everyday speech and in pause, these endings are often not pronounced fully, so you may hear something closer to:

• adh-dhahab jamīl

The -un ending is called tanwīn. Here it marks that جميل is:

• indefinite
• nominative

So in full MSA grammar:

• جَمِيلٌ = beautiful (indefinite, nominative)

This is normal for a predicate in a sentence like this.
In unvoweled everyday writing, you usually just see جميل without the ending written out.

Because الذهب is a masculine singular noun, and the predicate matches it in gender and number.

So:

• الذهب جميل
• not الذهب جميلة

If the subject were a feminine noun, then the predicate would normally be feminine too.

By itself, the consonants ذهب can belong to different words, including the verb he went in a fully marked form: ذَهَبَ.

But in this sentence, it is clearly the noun gold because:

• it has الـ: الذهب
• the sentence structure is a nominal sentence
• it is followed by جميل, which works naturally as a predicate

So here there is no ambiguity in context: it means the noun gold.

In careful MSA with full endings:

• adh-dhahabu jamīlun

In pause, which is very common when reading aloud:

• adh-dhahab jamīl

A rough English-style guide:

• adh-DHA-ha-bu ja-MEE-lun
  or in pause:
• adh-DHA-hab ja-MEEL

The stressed dh sound in ذهب is like the th in this, not the th in thin.

الذهب جميل is the natural way to say Gold is beautiful as a general statement.

Without الـ, ذهب جميل would usually not work well for that meaning in standard Arabic. It could sound incomplete or unnatural, because Arabic often uses the definite form for general categories and substances in this kind of statement.

So for a learner, the important pattern is:

• الذهب جميل = Gold is beautiful

You would say:

• الذهب الجميل

That is a noun + adjective phrase, not a full sentence.

Compare carefully:

• الذهب جميل = Gold is beautiful
• الذهب الجميل = the beautiful gold

This is a very important distinction in Arabic:

• if the second word is indefinite, it is often the predicate
• if the second word matches in definiteness with الـ, it is often an adjective describing the noun