A la taquilla de l'estació, una noia m'explica a quina andana arriba el tren.

Literally, A la taquilla de l'estació means At the ticket office of the station.

A few useful points:

• taquilla = ticket office / ticket window
• estació = station
• de l'estació = of the station

Why a?

• In Catalan, a can mean both to and at, depending on context.
• Here it gives the location: at the station ticket office.
• English often uses at, but Catalan commonly uses a in this kind of place expression.

So the opening sets the scene: At the station ticket office, ...

Because Catalan normally contracts or elides certain articles before vowels.

Here:

• de + l'estació = of the station
• The noun estació begins with a vowel, so the article is l' rather than la.

So:

• la taquilla = the ticket office
• l'estació = the station

This is very common in Catalan:

• l'home = the man
• l'escola = the school
• l'andana = the platform

Noia can mean either girl or young woman, depending on context.

In this sentence, una noia most naturally means:

• a young woman, or
• a girl, if the context suggests someone younger

Catalan noia often covers a range that English splits between girl and young woman.

So una noia m'explica... means something like:

• a young woman explains to me...
• or a girl tells me...

m' stands for em, the unstressed pronoun meaning to me or me, depending on the verb.

So:

• em explica = explains to me / tells me
• Before a vowel, em becomes m'
• That is why we get m'explica

In this sentence:

• una noia m'explica... = a young woman explains to me...

This kind of clitic pronoun is very common in Catalan:

• m'ajuda = helps me
• m'escolta = listens to me
• m'ensenya = shows me / teaches me

Because Catalan usually prefers the weak pronoun here.

So the normal form is:

• una noia m'explica...

You could say a mi for emphasis, but then it would sound more like:

• A mi, una noia m'explica...
• or Una noia m'ho explica a mi

That would mean something like to me, a young woman explains it or she explains it to me (specifically).

Without special emphasis, m' is the natural choice.

It can be either, depending on context.

Explicar often means:

• to explain
• to tell
• to describe

In this sentence, m'explica a quina andana arriba el tren is very natural as:

• she tells me which platform the train arrives at
• or she explains to me which platform the train arrives at

English often prefers tell here, while Catalan uses explicar very comfortably.

Because a quina andana arriba el tren is an embedded question, not a normal that-clause.

Compare:

• M'explica que el tren arriba a la via 3.
  = She explains/tells me that the train arrives at track 3.

But here the idea is which platform?, so Catalan uses an indirect question:

• M'explica a quina andana arriba el tren.
  = She tells me which platform the train arrives at.

So you do not add que before a quina andana.

Because quina has to agree with andana, and andana is feminine singular.

The forms are:

• quin = masculine singular
• quina = feminine singular
• quins = masculine plural
• quines = feminine plural

Since andana is feminine:

• quina andana = which platform

Examples:

• quin tren = which train
• quina andana = which platform
• quins bitllets = which tickets
• quines estacions = which stations

Because the verb arribar usually takes a before a destination or endpoint.

So:

• arribar a Barcelona = to arrive in/at Barcelona
• arribar a l'estació = to arrive at the station
• arribar a una andana = to arrive at a platform

That is why the question phrase includes a:

• a quina andana arriba el tren? = which platform does the train arrive at?

In English, the preposition often moves to the end:

• Which platform does the train arrive at?

In Catalan, it stays in front of the question word:

• A quina andana arriba el tren?

After an interrogative expression like a quina andana, Catalan very often uses verb-subject order:

• a quina andana arriba el tren

This is the most natural order here.

Literally, it is:

• at which platform arrives the train

But of course in English we say:

• which platform the train arrives at

So the Catalan order may feel a bit different, but it is normal and standard after question words.

It is grammatically present tense, but it can easily refer to a scheduled future event, just like English.

So arriba el tren can mean:

• the train arrives
• the train is arriving
• the train will arrive in a timetable/scheduled sense

In a station context, the meaning is often about an upcoming scheduled arrival.

This is very common in Catalan:

• El tren surt a les vuit. = The train leaves at eight.
• L'avió arriba demà. = The plane arrives tomorrow.

Yes. Andana is the normal Catalan word for a train platform.

So:

• andana = platform
• a quina andana = at which platform / which platform

This is a useful station word to remember alongside:

• estació = station
• taquilla = ticket office
• tren = train
• bitllet = ticket

Catalan often uses the definite article in places where English may or may not use it.

Here:

• arriba el tren = the train arrives

Catalan needs el tren because it is talking about a specific train in the situation.

In English, depending on style, you might translate the whole sentence as:

• A young woman tells me which platform the train arrives at
• or more naturally:
• A young woman tells me which platform my train arrives at
• ...which platform the train is arriving at

So el tren is fully normal in Catalan.

Yes. Even if the literal structure is clear, a more natural English version might be:

• At the station ticket office, a young woman tells me which platform the train arrives at.
• At the station ticket office, a young woman tells me which platform the train is coming into.
• At the station ticket office, a young woman tells me what platform the train arrives on.

That last version is especially natural in everyday English, even though the Catalan uses a quina andana literally at which platform.