أكتب خلال العمل.

In Arabic, the subject is often built into the verb itself.

• أكتب = I write / I am writing
• The initial أـ on the verb is the marker for I in the present tense.

So Arabic does not need a separate word for I here.
You could add أنا for emphasis:

• أنا أكتب خلال العمل. = I write during work.

But in normal speech or writing, أكتب by itself already tells you the subject is I.

It can mean both, depending on context.

In Modern Standard Arabic, the form أكتب can express:

• I write
• I am writing
• sometimes I do write

Arabic does not always separate simple present and present progressive the way English does. Context tells you which is meant.

So in different situations, أكتب خلال العمل could mean:

• I write during work
• I am writing during work

The verb comes from the root:

• ك-ت-ب

This root is connected with writing. From it you get many related words, such as:

• كتب = he wrote
• يكتب = he writes
• كتاب = book
• كاتب = writer
• مكتبة = library / bookstore

The dictionary form of the verb is usually:

• كتب = to write / he wrote

Then the present-tense first-person singular form is:

• أكتب = I write

خلال usually means during, throughout, or in the course of.

In this sentence:

• خلال العمل = during work / during working hours

It is a common formal MSA word for talking about time periods.

Examples:

• خلال اليوم = during the day
• خلال الأسبوع = during the week
• خلال الاجتماع = during the meeting

So here it introduces the time context in which the action happens.

العمل has the definite article الـ, so it means the work or work in a general, understood sense.

After خلال, Arabic often uses a definite noun when talking about a known period or activity:

• خلال العمل = during work / during the work period

If you said خلال عمل, that would usually sound incomplete unless another word follows it, such as:

• خلال عمل المشروع = during the work on the project

So خلال العمل is the natural standalone phrase.

Because خلال is followed by a noun in the genitive case.

In fully vowelled Arabic, you would read:

• أكتبُ خلالَ العملِ

Here:

• خلالَ is in the accusative because it functions as an adverbial expression of time
• العملِ is genitive because it comes after خلال

In normal unvowelled writing, these endings are not usually shown, but they are part of standard grammar.

A careful MSA pronunciation would be:

• ʾaktubu khilāla l-ʿamali

A simpler learner-friendly approximation is:

• ak-tu-bu khi-LA-la al-ʿa-ma-li

A few notes:

• أ here is a glottal stop plus a
• خ is the throaty sound like German Bach or Scottish loch
• ع in العمل is a deep consonant that has no exact English equivalent

If case endings are dropped in pause, learners may also hear something closer to:

• aktub khilāl al-ʿamal

Yes, this word order is normal.

The sentence is:

• أكتب = verb
• خلال العمل = time expression

So it is basically:

• I write during work

This is a very natural structure in Arabic.

You could also say:

• أكتب في العمل = I write at work
• أكتب أثناء العمل = I write while working / during work

These are similar, but not identical in nuance:

• خلال العمل emphasizes during the time of work
• في العمل emphasizes at work
• أثناء العمل also means during work, and is very common

They are close, but not the same.

• خلال العمل = during work, focusing on the time period
• في العمل = at work / in work, focusing more on location or general context

Compare:

• أكتب خلال العمل = I write during work hours
• أكتب في العمل = I write at work

So if you want to stress when, خلال is a strong choice.
If you want to stress where, في is often more natural.

No, it is grammatically complete.

The verb أكتب can be used:

• transitively: I write something
• intransitively in a general sense: I write

So أكتب خلال العمل can simply mean:

• I do writing during work
• I write while at work

If you want to add an object, you can:

• أكتب التقارير خلال العمل. = I write reports during work.
• أكتب رسائل خلال العمل. = I write messages during work.

But the original sentence is fine without one.

It is correct Modern Standard Arabic, but in everyday conversation many speakers would choose a more colloquial phrasing, depending on dialect.

Even within MSA, some alternatives may sound more natural in certain contexts, such as:

• أكتب أثناء العمل
• أكتب في العمل

So أكتب خلال العمل is good, correct, and understandable, especially in formal or written Arabic, but it may sound slightly formal compared with some everyday spoken choices.