رصيف القطار في المحطة.

A common pronunciation is:

raṣīfu l-qiṭāri fī l-maḥaṭṭa

If you say it in pause, as people usually do in normal speech, you will often hear something closer to:

raṣīf il-qiṭār fī l-maḥaṭṭa

A rough sound guide:

• ر = rolled or tapped r
• ص = emphatic s
• ط = emphatic t
• ح = a strong breathy h from the throat
• ق in MSA = deep q sound

So:

• رصيف = ra-seef
• القطار = al-qi-taar
• المحطة = al-ma-hat-ta

Because Arabic often expresses of by putting two nouns next to each other in a structure called iḍāfa (إضافة), often called the construct phrase.

So:

• رصيف القطار = literally platform the-train
• natural English = the train platform or the platform of the train

There is no separate word like of here. The relationship is shown by the noun combination itself.

This is a very common learner question.

In an iḍāfa construction, the first noun usually does not take الـ. Its definiteness is determined by the second noun.

So:

• رصيف قطار = a train platform / platform of a train
• رصيف القطار = the train platform / platform of the train

Because القطار is definite, the whole phrase رصيف القطار becomes definite.

Usually the train platform is the most natural English translation.

Arabic iḍāfa can often be translated in different ways, depending on what sounds best in English:

• كتاب الطالب = the student’s book
• باب البيت = the door of the house / the house door
• رصيف القطار = the train platform

So while platform of the train is grammatically possible, train platform is normally the better English wording.

في means in or at, depending on context.

So:

• في المحطة = in the station or at the station

The word المحطة means the station.
Because it comes after the preposition في, it means the platform is located there.

In Arabic, present-tense sentences often do not use a separate word for is / am / are.

So:

• رصيف القطار في المحطة literally looks like
  the train platform in the station
• but it means
  The train platform is in the station

This is a normal feature of Arabic nominal sentences. In the present tense, the linking verb is usually understood rather than spoken.

It can be understood as a complete nominal sentence in MSA:

• رصيف القطار = the subject
• في المحطة = the predicate / location phrase

So it means:

The train platform is in the station.

Without full context, Arabic without case endings can sometimes look phrase-like, but the most straightforward reading is as a complete sentence.

If you add the full case endings, it would be:

رَصِيفُ القِطارِ في المَحَطَّةِ

Why?

• رَصِيفُ: nominative, because it is the subject of the sentence
• القِطارِ: genitive, because it is the second noun in an iḍāfa
• المَحَطَّةِ: genitive, because it comes after the preposition في

In normal unvowelled writing, these endings are usually not written, and in pause they are often not pronounced either.

Because it is the second part of an iḍāfa construction.

In Arabic, the second noun in X of Y is put in the genitive:

• بابُ البيتِ = the door of the house
• رصيفُ القطارِ = the platform of the train

So القطارِ is genitive because it completes the possession/association relationship.

Because it comes after the preposition في.

In MSA, prepositions make the following noun genitive:

• في البيتِ = in the house
• في المدرسةِ = in the school
• في المحطةِ = in the station

So المحطةِ is genitive for a different reason from القطارِ:

• القطارِ is genitive because of iḍāfa
• المحطةِ is genitive because of the preposition في

محطة usually means station.

In different contexts it can mean:

• train station
• bus station
• stop
• station in a general sense

In this sentence, because القطار is mentioned, المحطة is naturally understood as the railway station.

Useful plurals are:

• رصيف → أرصفة = platforms / sidewalks
• قطار → قطارات = trains
• محطة → محطات = stations

These are worth memorizing because they are common travel words.

Yes, Arabic word order is flexible, and في المحطة رصيف القطار is possible.

But the meaning or emphasis may shift slightly:

• رصيف القطار في المحطة = a straightforward statement: The train platform is in the station
• في المحطة رصيف القطار = more emphasis on location, something like In the station is the train platform

The original order is the more neutral one for a beginner to learn first.