الدبوس على القماش.

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

So:

الدبوس على القماش
literally looks like the pin on the cloth/fabric,
but it means The pin is on the cloth/fabric.

If you wanted a past meaning, Arabic would use a verb such as كان:

كان الدبوس على القماش = The pin was on the cloth.

Yes. In normal context, it is a complete sentence in Arabic.

It is a nominal sentence: a sentence that begins with a noun rather than a verb.

• الدبوس = the topic/subject
• على القماش = the information about where it is

So the whole sentence means that the pin is located on the cloth.

The sentence breaks down like this:

• الدبوس = the مبتدأ (the subject/topic of the sentence)
• على القماش = the خبر (the predicate, telling us something about the subject)

More specifically:

• على = a preposition meaning on
• القماش = the noun after the preposition, meaning the cloth/fabric

So the structure is:

subject + prepositional phrase

This is very common in Arabic for location:

• الكتاب على الطاولة = The book is on the table
• القلم تحت الكرسي = The pen is under the chair

Because both nouns are definite.

The prefix ال is the Arabic definite article, usually equivalent to the.

So:

• دبوس = a pin
• الدبوس = the pin

and

• قماش = cloth / fabric
• القماش = the cloth / the fabric

In this sentence, the speaker is talking about a specific pin and a specific piece of cloth or fabric.

No, ال is not always pronounced the same way.

In الدبوس, the ل of ال is not pronounced fully because د is a sun letter. The sound assimilates:

• الدبوس is pronounced roughly ad-dabbuus

In القماش, the ل is pronounced because ق is a moon letter:

• القماش is pronounced roughly al-qamāsh

So this sentence is pronounced approximately:

ad-dabbuusu ʿalā al-qamāshi
or in normal pause without full endings:
ad-dabbuus ʿalā al-qamāsh

Because على is a preposition, and in Arabic prepositions come before the noun they govern, just as in English:

• on the cloth
• على القماش

So على must come first, then the noun.

Also, after a preposition, the noun is in the genitive case.

In a fully vowelled version, you would write:

الدبوسُ على القماشِ

Notice the kasra sound at the end of القماشِ.

Yes, in fully vocalized Arabic there are case endings, but they are usually omitted in everyday writing.

The fully vowelled form would be:

الدبوسُ على القماشِ

• الدبوسُ ends with ـُ because it is the subject of the nominal sentence
• القماشِ ends with ـِ because it comes after the preposition على

In normal Arabic text, these short vowels are usually not written, so learners often see:

الدبوس على القماش

Here, على means on, on top of, or on the surface of.

It often expresses contact with a surface.

Examples:

• الكتاب على الطاولة = The book is on the table
• الصورة على الحائط = The picture is on the wall

But like many prepositions, its exact translation can vary by context. Still, for beginners, on is the best basic meaning.

Because على and في describe different kinds of location.

• على = on, on top of, attached to the surface of
• في = in, inside

So:

• الدبوس على القماش = The pin is on the cloth
• الدبوس في القماش would suggest the pin is in the cloth, stuck into it or inside it

The choice depends on the exact meaning you want.

The most natural basic order here is:

الدبوس على القماش

That is the standard way to say The pin is on the cloth.

Arabic can sometimes change word order for emphasis, but for a learner, this basic order is the one to use first.

If you want to say There is a pin on the cloth, Arabic would more naturally use a different structure, such as:

هناك دبوس على القماش

So word order and structure can change the nuance.

Here القماش is functioning much like the English mass noun cloth or fabric.

So it does not necessarily mean one separate countable object the way a shirt or a towel would. It refers to the material or a piece of fabric, depending on context.

That is normal in Arabic. The exact English wording may vary:

• the cloth
• the fabric
• the material

But the Arabic structure stays the same.