Когда поезд подходит к вокзалу, я встаю и беру чемодан.

Because Когда поезд подходит к вокзалу is a subordinate time clause: When the train approaches the station. In Russian, a subordinate clause is normally separated from the main clause with a comma.

So the sentence is structured like this:

Когда поезд подходит к вокзалу, я встаю и беру чемодан.

The same would happen if the order were reversed:

Я встаю и беру чемодан, когда поезд подходит к вокзалу.

Подходит comes from подходить, which here means to approach / come up to.

So поезд подходит к вокзалу means the train is approaching the station, not necessarily that it has already arrived.

Compare:

• подходить к вокзалу = to approach the station
• приезжать на вокзал / на станцию = to arrive by transport
• приходить = to come on foot, or more generally to arrive in some contexts

For a train, подходит к вокзалу is very natural when the train is getting close.

Because the preposition к always takes the dative case.

So:

• вокзал = nominative
• к вокзалу = dative, meaning toward the station / up to the station

This is a very common pattern:

• к дому = toward the house
• к двери = toward the door
• к столу = toward the table

Чемодан is in the accusative case because it is the direct object of беру (I take).

However, for inanimate masculine singular nouns, the accusative form is the same as the nominative.

So:

• nominative: чемодан
• accusative: чемодан

If it were an animate masculine noun, the form would usually match the genitive instead.

Because this sentence describes a habitual or repeated situation:

Whenever the train approaches the station, I stand up and take my suitcase.

Russian often uses the present tense for regular actions like this.

The verbs are:

• подходит = approaches
• встаю = stand up / get up
• беру = take

If you wanted to describe one specific future occasion, Russian would normally use perfective future forms instead:

Когда поезд подойдет к вокзалу, я встану и возьму чемодан.

That means When the train approaches/gets to the station, I’ll stand up and take my suitcase.

Because in this sentence the actions are presented as part of a repeated pattern, not as one completed future event.

In Russian:

• imperfective present is used for habitual/repeated actions
• perfective future is used for one completed action in the future

So:

• я встаю и беру чемодан = I do this regularly / this is what I do
• я встану и возьму чемодан = I will do it once, in a particular future situation

Even though to stand up is naturally a bounded action, Russian still uses the imperfective present for habits.

Yes, it could.

Russian often omits subject pronouns when the verb ending already makes the subject clear.

So both are possible:

• Когда поезд подходит к вокзалу, я встаю и беру чемодан.
• Когда поезд подходит к вокзалу, встаю и беру чемодан.

Including я can make the sentence clearer, more explicit, or slightly more emphatic. Learners will often see pronouns used more often than native speakers would strictly need.

Yes, Russian word order is fairly flexible.

The sentence given is neutral and natural:

Когда поезд подходит к вокзалу, я встаю и беру чемодан.

But other orders are possible, for example:

• Я встаю и беру чемодан, когда поезд подходит к вокзалу.
• Когда поезд подходит к вокзалу, беру чемодан и встаю.
  This is grammatically possible, though it changes the flow and may sound less natural depending on context.

Russian word order often reflects focus, emphasis, and information structure, not just grammar.

Yes.

• вокзал usually means the station building / terminal
• станция usually means the station as a stop on the railway/metro line

In everyday use, there can be some overlap, but they are not always interchangeable.

In this sentence, к вокзалу suggests approaching the station area/building. In many real-life contexts, a speaker might also say something with станция, depending on exactly what they mean.

Because Russian has no articles like a/an/the.

Russian simply says:

• к вокзалу
• беру чемодан

Whether the meaning is a station, the station, a suitcase, or the suitcase is understood from context.

This is very normal in Russian and one of the biggest differences from English.

You would usually switch to perfective verbs:

Когда поезд подойдет к вокзалу, я встану и возьму чемодан.

Here is the contrast:

• Когда поезд подходит к вокзалу, я встаю и беру чемодан.
  = a usual, repeated action

• Когда поезд подойдет к вокзалу, я встану и возьму чемодан.
  = one specific future event

This is a very important Russian pattern:
present imperfective for habits, but future perfective for a single future occurrence.

The main stresses are:

• когдá
• по́езд
• подхóдит
• к вокзáлу
• я встаю́
• и беру́
• чемодáн

Stress matters a lot in Russian pronunciation, and it is not always predictable, so it is worth learning stressed forms together with new vocabulary and verb forms.