يعرف صديقي السعر الحالي.

Because Arabic often uses a verb–subject–object order, especially in simple statements.

So this sentence is structured as:

• يعرف = knows
• صديقي = my friend
• السعر الحالي = the current price

This is a very normal Arabic word order.

You can also say:

• صديقي يعرف السعر الحالي

That starts with the subject instead, which is also correct. It can sound slightly more focused on my friend.

In Arabic, the verb itself usually already includes the subject information.

يعرف means he knows.
So the he is built into the verb form.

That means Arabic does not need a separate pronoun here. If you added هو, it would usually be for emphasis, not because grammar requires it.

صديقي means my friend.

It is made from:

• صديق = friend
• ـي = my

So:

• صديق = friend
• صديقي = my friend

That final ـي is a possessive ending called a suffix pronoun. It attaches directly to the noun.

In Arabic, adjectives usually come after the noun they describe.

So:

• السعر = the price
• الحالي = current

Together:

• السعر الحالي = the current price

This is the normal Arabic pattern:

• noun first
• adjective second

Unlike English, which says current price, Arabic says price current.

Because in Arabic, adjectives match the nouns they describe in definiteness.

Here, السعر means the price, so it is definite.
Therefore the adjective must also be definite:

• السعر الحالي = the current price

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

• سعر حالي = a current price

So both words take الـ because they belong together as a definite noun phrase.

You know this mainly from the sentence structure and the meaning of the verb.

In this sentence:

• يعرف is the verb
• the noun right after it, صديقي, is the subject
• the thing being known, السعر الحالي, is the object

So:

• my friend = the one who knows
• the current price = the thing known

In fully vowelled Arabic, case endings would also help show this:

• صديقي = subject
• السعرَ الحاليَّ = object in the accusative

But in normal everyday writing, those endings are usually not written.

Because nouns with the my suffix (ـي) do not show the case ending clearly at the end in the usual way.

In other words, صديقي can be the subject here, but the nominative ending is not visible in normal spelling.

This is very common with words that have attached pronouns.

So even though صديقي is the subject, you do not see a separate ending like you might on some other nouns.

The basic past-tense form is عَرَفَ = he knew / came to know.

From that verb, the present-tense form is:

• يَعرِفُ = he knows

This comes from the root:

• ع ر ف

That root is often connected with meanings involving knowing, recognizing, or being familiar with.

They are similar, but not always identical.

• يعرف often means knows in the sense of is familiar with or recognizes
• يعلم often means knows in the sense of has knowledge of or is aware of a fact

In many simple sentences, both can be translated as know, but they are not always interchangeable in every context.

In this sentence, يعرف السعر الحالي is perfectly natural.

A careful pronunciation is approximately:

• yaʿrifu ṣadīqī as-siʿra al-ḥāliyya

A few notes:

• ṣ in ṣadīqī is an emphatic s
• ʿ in yaʿrifu is the Arabic letter ع, which has no exact English equivalent
• as-siʿra is written السعر, but ال sounds like as- here because س is a sun letter
• In normal speech and unvowelled text, learners often just read it more simply as
  yaʿrif ṣadīqī is-siʿr il-ḥālī depending on style and pronunciation habits

Yes. That is the fully vowelled, more formal version.

With case endings, it would be:

• يَعرِفُ صَديقي السِّعرَ الحاليَّ

Here:

• يَعرِفُ = indicative verb ending
• السِّعرَ = accusative object
• الحاليَّ = adjective matching the object in case, definiteness, gender, and number

In most modern writing, those short vowels are omitted, so you usually see:

• يعرف صديقي السعر الحالي

Both represent the same sentence.