مكتب البريد في الطابق الثاني قرب المصعد.

A careful MSA transliteration is maktab al-barīd fī aṭ-ṭābiq ath-thānī qurb al-miṣʿad.

A few pronunciation notes:

• مكتب = maktab
• البريد = al-barīd
• في = fī
• الطابق = aṭ-ṭābiq
• الثاني = ath-thānī
• قرب = qurb
• المصعد = al-miṣʿad

Two sounds that may feel unfamiliar:

• ط in الطابق is an emphatic t
• ع in المصعد is a voiced throat sound; in transliteration it is often shown with ʿ

Also, the ال in الطابق and الثاني assimilates in pronunciation because ط and ث are sun letters, so you hear aṭ-ṭābiq and ath-thānī, not al-ṭābiq or al-thānī.

Because Arabic usually omits the present-tense to be.

So مكتب البريد في الطابق الثاني قرب المصعد literally looks like: The post office on the second floor near the elevator

But in normal English, we say: The post office is on the second floor near the elevator.

This is a very common Arabic pattern called a nominal sentence. In the present tense, there is often no separate word for is / are. If you wanted the past, you would use a verb such as كان.

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

Literally, it is:

• مكتب = office
• البريد = the mail / the post

So the whole phrase is literally office of the mail, which corresponds to the post office.

In an iḍāfa:

• the first noun usually does not take ال
• the second noun shows whether the whole phrase is definite or not

Since البريد is definite, the whole phrase مكتب البريد is definite: the post office.

Not always. مكتب can mean:

• desk
• office

The exact meaning depends on context.

For example:

• مكتب المدير = the director’s office
• على المكتب = on the desk

But مكتب البريد is a fixed, very common expression meaning post office.

Because in Arabic, adjectives normally come after the noun they describe.

So:

• الطابق = the floor
• الثاني = the second

Together: الطابق الثاني = the second floor

Arabic adjectives also agree with the noun in:

• definiteness
• gender
• number
• case

That is why both words are definite here:

• الطابق
• الثاني

Because طابق is a masculine noun.

So the adjective must also be masculine:

• طابق → الثاني

If the noun were feminine, the adjective would be feminine too:

• غرفة = room
• الغرفة الثانية = the second room

So this is simple adjective agreement.

Yes, في very often means in, but it is also widely used where English would say on, especially with floors, levels, buildings, and locations.

So:

• في الطابق الثاني literally = in the second floor
• natural English = on the second floor

This is just a normal difference between the two languages. You should learn في الطابق... as the standard Arabic pattern.

قرب means near, but grammatically it behaves like a noun or adverbial expression meaning something like the vicinity of.

So:

• قرب المصعد = near the elevator
• more literally = in the vicinity of the elevator

The noun after قرب is connected to it in an iḍāfa-like relationship, which is why المصعد is understood as dependent on قرب.

This is why Arabic does not need an extra word like to or of in English. The structure itself carries that meaning.

A fully vocalized version can be written as:

مَكْتَبُ الْبَرِيدِ فِي الطَّابِقِ الثَّانِي قُرْبَ الْمِصْعَدِ

The endings are:

• مكتبُ because it is the subject/topic of the nominal sentence
• البريدِ because it is the second part of the iḍāfa
• الطابقِ because it comes after في
• الثانيِ because it is an adjective matching الطابق
• قربَ because it functions adverbially here
• المصعدِ because it is attached to قرب in an iḍāfa-type structure

In everyday reading and speech, these final short vowels are often not pronounced.

The original order is a very natural, neutral way to say it, but Arabic allows more flexibility than English.

For example, the location phrases can sometimes move for emphasis:

• مكتب البريد قرب المصعد في الطابق الثاني
• في الطابق الثاني قرب المصعد مكتب البريد in a more marked style

However, for a learner, مكتب البريد في الطابق الثاني قرب المصعد is the clearest basic pattern:

• thing being talked about first
• then the information about location

So yes, word order can change, but the original version is a good standard model to learn first.