يتحقق الزبون من تاريخ الشراء ومدة الاسترجاع في المتجر الإلكتروني.

Because this is a normal verbal sentence in Arabic. In Modern Standard Arabic, it is very common to begin a sentence with the verb:

• يتحقق الزبون... = The customer checks...

Arabic can also say:

• الزبون يتحقق...

But that is a subject-first structure. Both are possible, but the original sentence is using the very common verb + subject order.

Here يتحقق من means checks, verifies, or makes sure of.

This is important because the verb تحقّق can change meaning depending on whether it is followed by من:

• تحقّق من الشيء = to verify/check something
• تحقّق الشيء = something was realized / came true / was achieved

So in your sentence, من is not being translated literally as from. It is simply the preposition that goes with this verb in the sense of verify/check.

Yes. الزبون is the subject, meaning the customer.

If full case endings were written, it would be الزبونُ, showing the nominative case, which is the normal case for the subject of the sentence.

So the structure is:

• يتحقق = checks / verifies
• الزبون = the customer

This is because of the sun-letter / moon-letter rule.

• In الزبون, the letter ز is a sun letter, so the ل of ال is not pronounced separately. You say something like az-zabūn.
• In الشراء, the letter ش is also a sun letter, so it sounds like ash-shirāʾ.
• In المتجر, the letter م is a moon letter, so the ل is pronounced: al-matjar.

So the spelling stays the same, but the pronunciation changes depending on the first letter of the noun.

Both are iḍāfa constructions, often called a genitive construction or noun + of + noun structure.

• تاريخ الشراء = date of the purchase = purchase date
• مدة الاسترجاع = duration of the return = return period

In an iḍāfa:

1. The first noun is the main thing being described.
2. The second noun tells you what it is connected to.
3. The first noun usually does not take ال.
4. The second noun is in the genitive case.

So these phrases are very natural Arabic ways to express ideas that English often turns into compound nouns.

Because in an iḍāfa, the second noun can be definite, and when it is definite, the whole phrase becomes definite.

So:

• تاريخ شراء = a purchase date / date of a purchase
• تاريخ الشراء = the purchase date / date of the purchase

Likewise:

• مدة استرجاع = a return period
• مدة الاسترجاع = the return period

The first noun in the iḍāfa usually does not take ال, but the second noun can.

Because one preposition can govern two nouns joined by و.

So:

• من تاريخ الشراء ومدة الاسترجاع

means:

• of/from the purchase date and the return period

Arabic does not need to repeat من before the second noun if both nouns belong to the same structure. Repeating it is possible in some contexts, but it is not necessary here.

They are nouns, specifically verbal nouns (called maṣdars in Arabic).

• الشراء = purchasing / purchase
• الاسترجاع = returning / return

Even though they come from verbs, they function as nouns in this sentence. That is why they can appear:

• after ال
• inside an iḍāfa construction
• after a preposition

This is very common in Arabic.

Because الإلكتروني is an adjective describing المتجر, and Arabic adjectives must agree with the noun they describe.

They agree in:

• definiteness
• gender
• number
• case

So since the noun is المتجر (the store), the adjective must also be definite:

• المتجر الإلكتروني = the electronic/online store

If the noun were indefinite, the adjective would also be indefinite:

• متجر إلكتروني = an online store

A fully marked version would look like this:

يتحققُ الزبونُ من تاريخِ الشراءِ ومدّةِ الاسترجاعِ في المتجرِ الإلكترونيِّ

The important endings are:

• يتحققُ = verb in the indicative
• الزبونُ = nominative, because it is the subject
• تاريخِ = genitive after من
• الشراءِ = genitive as the second noun of the iḍāfa
• مدّةِ = also genitive after من
• الاسترجاعِ = genitive in the iḍāfa
• المتجرِ = genitive after في
• الإلكترونيِّ = genitive adjective agreeing with المتجر

In normal Arabic writing, these short vowels are usually omitted.

Yes, في literally means in.

So word-for-word, في المتجر الإلكتروني is in the online store. In English, though, we often say:

• on the online store
• on the website
• in the online shop

Arabic commonly uses في for this kind of digital or commercial context, even when English might prefer on.

Yes. Depending on context, الزبون can mean:

• customer
• client
• sometimes shopper

In this sentence, customer is the most natural choice, because the sentence is about checking purchase and return information in an online store context.