صديقي لا يزال في المكتب، وسوف يعود الى البيت بعد ساعة.

In the present tense, Arabic usually does not use a separate word for is / am / are.

So instead of saying something like My friend is in the office, Arabic simply says:

• صديقي في المكتب = My friend is in the office

In your sentence, the first clause is a little richer:

• صديقي لا يزال في المكتب

This means My friend is still in the office.

Here, لا يزال gives the idea of still / continues to be, so you do not need a separate present-tense is.

لا يزال means still or continues to be.

So:

• لا يزال في المكتب = he is still in the office

A helpful way to think of it is:

• يزال comes from a verb related to ceasing/disappearing
• لا يزال literally gives the sense of has not ceased
• idiomatically, it means still or is still

This is a very common MSA expression.

Examples:

• لا يزال نائمًا = He is still asleep
• لا تزال المدرسة مغلقة = The school is still closed

Because the ـي at the end is a possessive suffix meaning my.

Breakdown:

• صديق = friend
• صديقي = my friend

This suffix attaches directly to the noun.

Other examples:

• كتابي = my book
• بيتي = my house
• أستاذي = my teacher

So صديقي is not two separate words in Arabic; it is one word meaning my friend.

Arabic often adds possessive pronouns directly to nouns.

With صديق, when you add ـي (my), you get:

• صديق + ي = صديقي

In fully vowelled Arabic, this is often understood as coming from صديقِي.

Also, because the noun is now definite through possession (my friend), it does not take tanwīn.

Compare:

• صديقٌ = a friend
• صديقي = my friend

So possession changes both the meaning and the grammatical form.

Because it matches صديقي, which is masculine singular.

Arabic verbs agree with the subject in gender and number. Since صديقي = my friend is masculine singular, the verb is masculine singular too:

• لا يزال = he is still

  If the subject were feminine, you would say:

• صديقتي لا تزال في المكتب = My female friend is still in the office

So the form changes depending on who or what the subject is.

The و simply means and.

So:

• و = and
• سوف يعود = he will return

Together:

• وسوف يعود = and he will return

Arabic often uses و very freely to connect clauses, much like and in English.

سوف is a future marker. It means that the verb refers to the future:

• يعود = he returns / he is returning
• سوف يعود = he will return

Arabic has two common ways to mark the future:

• سوف يعود
• سيعود

Both mean he will return.

In many contexts, they are very similar. A common learner-friendly rule is:

• سـ is shorter and often feels a bit lighter or more immediate
• سوف can sound a bit more formal or slightly more emphatic

In Modern Standard Arabic, both are normal.

يعود means he returns / he will return.

It comes from the root ع-و-د, which is connected with returning or going back.

So:

• عاد = he returned
• يعود = he returns / he will return

Because سوف is already marking the future, يعود here is understood as:

• سوف يعود = he will return

Arabic does not need a separate word for will beyond the future marker.

Because the verb already contains the subject information.

يعود by itself means he returns.

The يـ at the beginning tells you it is third person masculine singular in the imperfect tense.

So Arabic often does not need an explicit subject pronoun if the subject is already clear.

In this sentence, the subject is already given as صديقي, so there is no need to add هو.

In standard spelling, yes, it is normally written:

• إلى البيت

The form الى without the hamza is very common in casual typing, informal writing, or when people omit some orthographic details.

So:

• إلى = standard spelling
• الى = commonly seen informal spelling

For formal Modern Standard Arabic, learners should write إلى.

It means to.

So:

• إلى البيت = to the house / home

Arabic often uses the house where English would simply say home.

So:

• إلى البيت literally = to the house
• but naturally it often means = home

This is very common. Arabic frequently uses the definite article ال in places where English does not.

Compare:

• ذهب إلى البيت = He went home
• literally: He went to the house

So even though البيت has the, the natural English translation may still be home.

In this sentence, بعد ساعة usually means in an hour or after one hour from now.

Breakdown:

• بعد = after
• ساعة = an hour / one hour

So literally it is after an hour, but in natural English, the best translation in many contexts is:

• in an hour

For example:

• سأعود بعد ساعة = I’ll be back in an hour

So both ideas are related, but in an hour is often the smoother English translation.

Because it means an hour / one hour, not the hour.

So:

• ساعة = an hour
• الساعة = the hour / the clock / the time, depending on context

In time expressions, Arabic often uses an indefinite noun like this:

• بعد دقيقة = in a minute
• بعد ساعة = in an hour
• بعد يوم = after a day / in a day

That is why there is no الـ on ساعة.

Yes. In fully vowelled formal Arabic, the sentence would have case endings and other short vowels, but in normal everyday writing they are usually omitted.

A fully vocalized version could look like:

• صديقي لا يزالُ في المكتبِ، وسوف يعودُ إلى البيتِ بعدَ ساعةٍ.

Some points:

• صديقي: the final pronunciation depends on the possessive form
• المكتبِ: after في, the noun is genitive
• يعودُ: indicative ending
• البيتِ: after إلى, the noun is genitive
• بعدَ: often treated with an accusative ending in this structure
• ساعةٍ: genitive after بعد

Learners usually meet these endings later, since ordinary Arabic texts often leave them unwritten.

A simple pronunciation guide is:

ṣadīqī lā yazālu fī al-maktab, wa-sawfa yaʿūdu ilā al-bayt baʿda sāʿah

A few notes:

• ص = an emphatic s
• ʿ in yaʿūdu and baʿda represents the letter ع
• dh / th are not used here; this sentence is mostly straightforward once you know the sounds
• سوف is pronounced sawfa
• يعود is yaʿūdu, with a long ū

If you want a more natural connected reading:

ṣadīqī lā yazālu fī l-maktab, wa-sawfa yaʿūdu ilā l-bayt baʿda sāʿah

Yes, but the meaning changes.

• صديقي في المكتب = My friend is in the office
• صديقي لا يزال في المكتب = My friend is still in the office

So لا يزال adds the important idea of continuation.

It suggests something like:

• he was there before
• he is there now
• he has not left yet

Without لا يزال, you lose that nuance.

Yes, it is natural and clear MSA.

A more fully standard spelling would be:

• صديقي لا يزال في المكتب، وسوف يعود إلى البيت بعد ساعة.

This is a good example of normal written Arabic:

• a nominal-style present statement in the first clause
• a future clause with سوف
• a common time expression with بعد ساعة

So for a learner, this is a very useful sentence pattern to know.