eki no kaidan de subette koronda onna no hito ga ita node, kega ga nai ka sinpaisita.

In both places, の links one noun to another.

• 駅の階段 = the station's stairs / the stairs at the station
• 女の人 = literally female person, so woman

So の is not only for possession. It can also show description, category, or association.

A good way to think about it is:

• A の B = B related to A

That relation can be possession, location, type, material, and so on.

で marks the place where an action happens.

Here, the actions are:

• 滑って = slipping
• 転んだ = falling down

So 駅の階段で means on the station stairs / at the station stairs, as the location where those actions happened.

If you used に here, it would not sound right for the location of this action. For action location, で is the normal particle.

It means slipped and fell.

• 滑る = to slip
• 転ぶ = to fall down

The て-form in 滑って connects the first action to the second. So the sequence is:

1. she slipped
2. then she fell

Using both verbs is natural because slipping is the cause and falling is the result. It is not redundant; it gives a more specific picture than just saying 転んだ.

Japanese does not use words like who, that, or which in the same way English does for relative clauses.

Instead, the whole verb phrase comes directly before the noun:

• 滑って転んだ女の人
• literally: slipped-and-fell woman

So in natural English, this becomes:

• the woman who slipped and fell

This is a very common Japanese pattern:

• 昨日会った人 = the person I met yesterday
• 本を読んでいる学生 = the student who is reading a book

So here, 滑って転んだ is simply modifying 女の人.

There are two separate points here.

1. Why が?
In 女の人がいた, が marks the person who existed/was there.

So this part means:

• there was a woman
• more specifically: there was a woman who had slipped and fallen

This use of が is very common when introducing new information.

2. Why いた?
Japanese uses:

• いる for animate beings such as people and animals
• ある for inanimate things

Because a woman is a person, the correct verb is いた, the past form of いる.

ので means because or so.

In this sentence:

• …女の人がいたので、けががないか心配した
• Because there was a woman who slipped and fell, I worried about whether she was injured

Compared with から, ので often sounds a little softer, more explanatory, and a bit more objective.

Very roughly:

• から = more direct, sometimes more personal
• ので = more explanatory, often smoother in narration

In a sentence like this, ので sounds very natural.

This expression is based on:

• けががある = there is an injury / someone is injured
• けががない = there is no injury / someone is uninjured

So けががないか literally means:

• whether there was no injury

But in natural English, that usually comes out as:

• whether she was okay
• whether she was injured
• whether she had any injuries

Japanese often expresses this idea through the existence or non-existence of injury, while English usually phrases it differently.

So even though the literal wording is whether there was no injury, the natural meaning is just that the speaker was worried about the woman's condition.

Here, か marks an embedded question.

So instead of asking the listener a question, it puts a question-like idea inside a larger sentence.

• けががないか心配した
• I worried about whether she was injured / whether she was okay

This is like English whether.

Other examples:

• 来るか分からない = I don't know whether he will come
• 大丈夫か聞いた = I asked whether she was okay

So か does not always mean the whole sentence is a direct question.

The subject is omitted because Japanese often leaves out information that is clear from context.

Here, the understood subject is most naturally:

• the speaker
• the narrator
• in English, usually I

So the sentence means that I was worried.

Likewise, the person who might be injured is understood to be the woman who slipped and fell.

Japanese often avoids repeating pronouns like I, she, or they when the context already makes them clear.

Yes, 女の人 is a very natural everyday expression for woman.

• 女の人 = common, conversational, everyday
• 女性 = more formal, more neutral in official or written contexts

So in a normal narrative sentence like this, 女の人 sounds very natural.

Also, note that 女 by itself can sound blunt depending on context, so learners are often safer using:

• 女の人
• 女性

until they get a better feel for nuance.

That is a very normal feature of Japanese.

Japanese often puts descriptive information before the noun it describes, and it also places the main verb at the end of the clause.

So the structure is roughly:

• [station stairs + on] [slipped and fell] [woman] [there was], so [whether there was injury] [worried]

More naturally grouped:

• 駅の階段で滑って転んだ女の人 = the woman who slipped and fell on the station stairs
• がいたので = because there was
• けががないか心配した = I worried about whether she was injured

This can feel very different from English at first, but it is one of the core patterns of Japanese sentence structure.