المشتري يقرأ إعلان البيع.

A careful MSA reading is:

al-mushtarī yaqraʾu iʿlāna al-bayʿi

With full vowels, it is:

المُشْتَرِي يَقْرَأُ إِعْلَانَ البَيْعِ

A few pronunciation notes:

• المشتري = al-mushtarī
• يقرأ = yaqraʾu; the ʾ shows a hamza, a little catch in the throat
• إعلان = iʿlān; the ʿ is the letter ع
• البيع = al-bayʿ

المشتري means the buyer.

Grammatically, it is an active participle from the verb اشترى (to buy). Literally, it means the one who buys, but in normal usage it functions as a regular noun: buyer.

So:

• مشتري = buyer / a buyer
• المشتري = the buyer

يقرأ is a present/imperfect tense verb, third-person masculine singular.

That means it matches a subject like he or a singular masculine noun such as المشتري.

So يقرأ can mean:

• he reads
• he is reading
• sometimes he does read, depending on context

The prefix يـ is one of the signals that the verb is in the present/imperfect.

This is the Arabic iḍāfa construction, often called the construct phrase.

إعلان البيع literally means:

• advertisement of the sale

In natural English, that may become:

• the sale advertisement
• the sales ad
• the advertisement for the sale, depending on context

In Arabic, instead of inserting a separate word for of, two nouns are placed together:

• إعلان = advertisement
• البيع = the sale

So إعلان البيع = advertisement of the sale

Because it is the first noun in an iḍāfa.

In an iḍāfa:

• the first noun normally does not take الـ
• the first noun also does not take tanwīn

So you get:

• إعلانُ البيعِ
• إعلانَ البيعِ

not:

• الإعلان البيع
• إعلانٌ البيع
• إعلانًا البيع

This is a very common Arabic pattern. The definiteness of the whole phrase is often determined by the second noun.

البيع means the sale or selling, depending on context.

It is a verbal noun from the verb باع (to sell). In this sentence, it works like the noun sale in English.

So:

• باع = he sold
• البيع = the sale / selling

In إعلان البيع, it gives the type or content of the advertisement: it is an advertisement connected to a sale.

In a fully analyzed version:

• المشتري = subject, so it is nominative
• إعلان = direct object of يقرأ, so it is accusative
• البيع = second term of an iḍāfa, so it is genitive

So the fully vowelled sentence is:

المشتري يقرأ إعلانَ البيعِ

One useful detail: المشتري is a special type of noun ending in -ī, so its nominative ending is not obvious in the normal spelling. Learners often just need to know that it is still the subject and therefore nominative.

Yes. Arabic allows more than one normal word order.

This sentence is subject–verb–object:

المشتري يقرأ إعلان البيع

You could also say:

يقرأ المشتري إعلان البيع

That is verb–subject–object, which is also very common in Arabic.

Both are correct. The version with the subject first can sound a bit more like it is highlighting the buyer.

It can mean either one.

In MSA, the present/imperfect often covers both:

• The buyer reads the sale advertisement
• The buyer is reading the sale advertisement

Context tells you which is more natural.

If the sentence appears by itself, either reading is possible.