На следующей станции мы пересядем в другой вагон, потому что в этом слишком душно.

Russian uses на станции with the meaning at the station or when we get to the station.

So:

• на станции = at the station
• в станции would usually sound wrong here

In this sentence, На следующей станции means something like At the next station or When we reach the next station.

Also notice the form следующей. After на in this meaning, станция is in the prepositional case:

• следующая станция → nominative
• на следующей станции → prepositional

Пересядем is from the verb пересесть, which means:

• to move and sit somewhere else
• to change seats / move to another carriage / transfer

In this context, it means we’ll move to another carriage.

The form пересядем is:

• 1st person plural: we
• future tense
• from a perfective verb

So мы пересядем = we will switch/move over.

Because the action will happen later, at the next station.

Russian perfective verbs do not have a true present tense. Their “present-looking” forms actually refer to the future:

• пересесть = perfective
• мы пересядем = we will move/switch

If you used an imperfective verb, you would get something like:

• будем пересаживаться = we will be changing / we’ll be in the process of moving

But here Russian prefers the perfective because it is a single completed action: we’ll change carriages.

Because the first в shows motion toward something, while the second shows location.

1. в другой вагон

This means into another carriage. Since there is movement, Russian uses the accusative case:

• другой вагон → accusative masculine singular = другой вагон

2. в этом

This means in this one. Here there is no movement; it describes location, so Russian uses the prepositional case:

• в этом = in this one

The noun вагоне is omitted because it is understood from context. Full version:

• в этом вагоне

So the sentence contrasts:

• move into another carriage
• because in this one it is too stuffy

Both are possible.

• в этом вагоне = full form, very explicit
• в этом = shorter, natural when the noun is obvious

Since the sentence already mentioned вагон, Russian can drop it and just say в этом, meaning in this one.

English does the same:

• Let’s go to another car, because in this one it’s too stuffy.

Here вагон means a train car / railway carriage.

Depending on the variety of English, you might translate it as:

• carriage
• railcar
• train car

It does not mean the whole train. It means one section of the train.

Другой is the most common and natural word for another / different / other in this kind of sentence.

So:

• в другой вагон = into another carriage

Russian has other words that can sometimes mean similar things, such as иной, but другой is the normal everyday choice here.

Душно means stuffy, airless, or oppressively warm and lacking fresh air.

Russian often uses short predicative words like this without a separate verb in the present tense:

• Здесь холодно. = It is cold here.
• Мне скучно. = I am bored.
• В этом слишком душно. = It is too stuffy in this one.

In the present tense, Russian usually does not use a word for is. So literally:

• в этом слишком душно = in this one too stuffy

But natural English adds it is.

Слишком means too or excessively.

So:

• душно = stuffy
• слишком душно = too stuffy

It tells you the condition is not just noticeable, but excessive enough to motivate the action of moving.

Russian word order is flexible, but this order is very natural.

• потому что = because
• в этом comes early to emphasize the place: in this one
• слишком душно gives the reason/condition: it’s too stuffy

A fuller version could be:

• ..., потому что в этом вагоне слишком душно.

Russian often places the location before the predicative word:

• Здесь жарко.
• Дома тихо.
• В машине холодно.

So в этом слишком душно sounds very normal.

Sometimes yes, but transfer can sound a bit misleading in English.

In Russian, пересесть can mean:

• to change seats
• to switch to another carriage
• to transfer to another vehicle

Here, because of в другой вагон, it clearly means moving into another carriage of the same train, not changing trains entirely.

So the best translations are things like:

• At the next station we’ll move to another carriage, because this one is too stuffy.
• We’ll change to another car at the next station, because it’s too stuffy in this one.

Следующей is the prepositional singular feminine form of следующий.

Here is the logic:

• станция is feminine
• after на in на станции, you need the prepositional case
• so следующая becomes следующей

Pattern:

• следующая станция = nominative
• на следующей станции = prepositional

So the adjective has to agree with станции in:

• gender: feminine
• number: singular
• case: prepositional

Yes. In context, it often has both ideas at once.

Russian frequently uses a place phrase like this to indicate the point at which something will happen:

• На следующей станции мы пересядем...

This can be understood as:

• At the next station...
• When we get to the next station...

English may choose either version depending on style.