На перроне было холодно, поэтому я решила не ждать на улице и спустилась в переход.

На перроне means on the platform / at the platform.

Here на is a preposition of location, so перрон goes into the prepositional case:

• nominative: перрон
• prepositional: на перроне

Russian often uses на with places seen as surfaces or open public areas, including transport platforms: на вокзале, на станции, на платформе, на перроне.

Because this is an impersonal sentence describing a condition, not describing a noun.

• было холодно = it was cold
• холодно is a predicative adverb / category-of-state word
• было is the neuter past-tense form of быть, often used in impersonal statements

So Russian expresses weather, temperature, and general conditions this way:

• Было холодно. = It was cold.
• Было темно. = It was dark.
• Было трудно. = It was difficult.

If you said был холодный, that would need a masculine noun:

• День был холодный. = The day was cold.

Because Russian very often uses subjectless impersonal constructions for weather, temperature, and general surroundings.

English uses a dummy subject it:

• It was cold

Russian usually does not need an equivalent word:

• Было холодно

So the sentence does not literally say it anywhere. That is completely normal in Russian.

Поэтому means therefore / so / that’s why. It introduces the result or consequence of what was said before.

Structure here:

• На перроне было холодно = the situation
• поэтому я решила... = the consequence

So it links the two ideas very naturally:

• It was cold on the platform, so I decided...

Russian past tense agrees with the gender of the subject.

The infinitive is решить. In the past tense:

• я решил = I decided, if the speaker is male
• я решила = I decided, if the speaker is female

So решила tells you the speaker is female.

After verbs like решить (to decide), Russian normally uses an infinitive for the action decided on.

So:

• решила ждать = decided to wait
• решила не ждать = decided not to wait

This is very similar to English decided to wait / decided not to wait.

Because ждать here refers to the general action/state of waiting, not to a single completed waiting event.

• ждать is imperfective
• it focuses on the process or ongoing activity

After решила не..., Russian often chooses the imperfective when talking about refusing to engage in an activity at all:

• решила не ждать = decided not to wait

A perfective form like подождать would suggest wait for a while as a bounded action, which is not the main idea here.

They are related, but not identical.

• на перроне = on the station platform
• на улице = outside / outdoors

The first phrase gives the exact place where it was cold. The second phrase expresses the broader idea of being outside in the open air.

So the logic is:

• it was cold on the platform,
• therefore I decided not to wait outside,
• and instead went down into the passage.

Спустилась is the past tense feminine form of спуститься, which means to go down / descend.

Breakdown:

• спуститься = perfective verb
• спустилась = feminine past tense
• it agrees with the same female speaker as решила

It is perfective because it presents the movement as a completed action:

• she went down into the passage

If the speaker were male, it would be спустился.

That is the reflexive marker of the verb спуститься.

Many Russian motion/change-of-position verbs exist in pairs, and the reflexive form often becomes the normal intransitive verb for the person moving:

• спустить = to lower something
• спуститься = to go down oneself

So here the speaker is not lowering something else; she herself goes down.

Because Russian uses different cases after в depending on whether you mean motion into a place or location in a place.

• в переход = into the passage → accusative
• в переходе = in the passage → prepositional

Here the verb спустилась expresses movement toward/into the underpass, so Russian uses the accusative:

• спустилась в переход

Here переход usually means an underground pedestrian passage / underpass, especially the kind used at stations or near metro entrances.

In this context, it is the place you go down into from the platform or station area to get out of the cold.

So it is not just the abstract idea of a crossing; it refers to a real physical passageway.

Because the same subject continues across both verbs:

• я решила
• и спустилась

Russian often leaves out repeated subjects when they are obvious. English can do something similar:

• I decided not to wait outside and went down into the passage.

Repeating я would also be possible in some contexts, but it is unnecessary here.

Both are possible, but the given order puts the location first for emphasis or scene-setting.

• На перроне было холодно = On the platform, it was cold.
• Было холодно на перроне = It was cold on the platform.

Starting with На перроне helps establish the setting immediately. Russian word order is flexible, and changes often affect emphasis more than basic meaning.

Because поэтому connects two clauses, and Russian normally separates them with a comma.

Here the sentence has:

1. На перроне было холодно
2. поэтому я решила не ждать на улице и спустилась в переход

The comma marks the boundary between the cause/situation and the result.