حالما يستلم صديقي تأكيد الحجز، يعرف موعد المغادرة.

حالما is a conjunction meaning as soon as. It introduces a time clause.

In this sentence, حالما يستلم صديقي تأكيد الحجز means as soon as my friend receives the booking confirmation.

A very close alternative in MSA is ما إن or sometimes عندما depending on style and exact nuance, but حالما specifically gives the idea of something happening immediately after something else.

In Arabic, the imperfect verb does not only mean present time. It can also express:

• present
• future
• habitual actions
• general truths

After a time word like حالما, the imperfect is very natural even when English would often use the present in the time clause and the future in the main clause.

So Arabic can say:

• حالما يستلم... يعرف...

even if English might say:

• As soon as he receives..., he will know...

Arabic often leaves the future meaning to context instead of adding a future marker.

Because it is not necessary here.

The word حالما already creates a future sequence: first he receives the confirmation, then he knows the departure time. That context is enough to make the meaning future.

You could sometimes add a future marker in other sentences for extra clarity, but in a sentence like this, plain imperfect verbs are normal and natural.

يستلم is the imperfect, third-person masculine singular form of the verb استلم.

So it means:

• he receives
• he takes delivery of
• he gets

Its root is س ل م. In this form, the verb often has the sense of receiving or taking possession of something officially or physically.

Here:

• يستلم صديقي تأكيد الحجز = my friend receives the booking confirmation

Because Arabic often prefers verb-first word order, especially in formal written language like MSA.

So:

• يستلم صديقي... = verb + subject
• صديقي يستلم... = subject + verb

Both are possible, but verb + subject is very common in MSA.

Using صديقي يستلم would usually put a bit more emphasis on my friend.

صديقي is made of:

• صديق = friend
• ـي = my

So صديقي means my friend.

The ـي is a attached possessive pronoun. Arabic often expresses possession this way instead of using a separate word for my.

Because this is an iḍāfa construction, often called a construct phrase.

تأكيد الحجز literally means:

• confirmation of the booking

In an iḍāfa:

• the first noun usually does not take ال
• the second noun can be definite or indefinite
• the whole phrase gets its definiteness from the second noun

So:

• تأكيد الحجز = the booking confirmation / confirmation of the booking

Because الحجز is definite, the whole phrase is definite.

This is also an iḍāfa phrase.

• موعد = time / موعد / scheduled time / appointment
• المغادرة = the departure

So موعد المغادرة means:

• the departure time
• or sometimes the time of departure

Again, the first noun موعد does not take ال because it is the first part of an iḍāfa, and the second noun المغادرة makes the whole phrase definite.

Yes, يعرف and يعلم can both relate to knowing, but they are not always used in exactly the same way.

In this sentence, يعرف موعد المغادرة is natural and idiomatic for he knows / finds out the departure time.

Very roughly:

• يعرف often works well for knowing information, people, facts, names, times, etc.
• يعلم can sound a bit more formal or more like to know/be aware that...

So يعرف موعد المغادرة is perfectly normal here.

Because the verb itself already tells you the subject is he.

يعرف means he knows. Arabic verbs usually include person, number, and often gender within the verb form.

Also, because the subject has already been mentioned as صديقي, Arabic does not need to repeat a separate pronoun like هو.

So the subject of يعرف is understood to be the same person: my friend.

Functionally, the cases are:

• صديقي = subject of يستلم, so it is nominative
• تأكيد = direct object of يستلم, so it is accusative
• الحجز = second part of iḍāfa, so it is genitive
• موعد = direct object of يعرف, so it is accusative
• المغادرة = second part of iḍāfa, so it is genitive

A fully vocalized version would look like this:

• حالما يستلمُ صديقي تأكيدَ الحجزِ، يعرفُ موعدَ المغادرةِ.

One small detail: with صديقي, the case is understood from grammar, but the attached ـي means you do not see a normal final short vowel the way you would on a bare noun.

It can depend on context.

With حالما, this sentence most naturally suggests a sequence such as:

• as soon as he receives the confirmation, he knows the departure time

That can refer to:

• one expected future event, or
• a general pattern

Without more context, many readers will understand it as a straightforward future sequence. But grammatically, Arabic imperfect verbs can also allow a more general or habitual reading in the right context.

It is helpful, but not the core of the grammar.

The comma ، in Arabic marks a pause between the time clause and the main clause:

• حالما يستلم صديقي تأكيد الحجز، يعرف موعد المغادرة.

It works much like the English comma after an opening clause:

• As soon as my friend receives the booking confirmation, he knows the departure time.

You may see punctuation used a little flexibly in Arabic writing, but here the comma is natural and clear.