Я посмотрела на табло и увидела, что наш поезд задерживается на десять минут.

Because the speaker is female.

In the past tense, Russian verbs agree with the subject in gender and number:

• посмотрел / увидел = masculine
• посмотрела / увидела = feminine
• посмотрело / увидело = neuter
• посмотрели / увидели = plural

So Я посмотрела... и увидела... tells you that I is a woman.

Because the sentence describes two completed actions in the past:

1. Я посмотрела на табло — I looked at the board.
2. и увидела — and I saw / noticed

Both happened as finished events.

This is very common in Russian storytelling: one completed action leads to another.

They are perfective because the sentence is about single, completed actions, not ongoing processes.

• смотреть = to look, to be looking

• посмотреть = to take a look

• видеть = to see
• увидеть = to catch sight of, to notice, to see as a completed event

So:

• Я смотрела на табло would mean I was looking at the board
• Я посмотрела на табло means I looked at the board / took a look

And:

• я видела often means I saw / I have seen / I was able to see
• я увидела means I saw, noticed, caught sight of at that moment

In this sentence, the perfective forms fit the idea of a quick sequence: looked → noticed.

They describe two different stages:

• посмотрела на табло = directed her eyes at the board
• увидела, что... = noticed / realized from what she saw that...

So the first verb is about the act of looking, and the second is about the result of that look.

This is very natural in Russian:

• Я посмотрел и увидел...
• Она посмотрела и заметила...

It is the accusative, because смотреть на takes the accusative:

• смотреть на кого? на что?

So:

• на стол
• на дом
• на табло

However, табло is an indeclinable noun, so its form does not change. The nominative and accusative look the same:

• табло
• на табло

That is why you do not see a visible ending change here.

Табло usually means a display board, scoreboard, information board, or electronic board.

In the context of trains, it normally means the departure/arrival board at a station.

It is a borrowed word and is usually indeclinable, which is why its form stays табло in different cases.

Что introduces a subordinate clause: that...

So:

• увидела, что наш поезд задерживается... = saw/noticed that our train is delayed...

This is one of the most common uses of что in Russian.

Compare:

• Я знаю, что... = I know that...
• Я думаю, что... = I think that...
• Я увидела, что... = I saw/noticed that...

Because наш поезд is the subject of the subordinate clause:

• что наш поезд задерживается...

The subject is in the nominative case, so both words are nominative:

• наш = nominative masculine singular
• поезд = nominative masculine singular

They agree with each other.

This is a very common point for English speakers.

Russian does not always shift tenses backward the way English often does. After a past-tense verb like увидела, Russian can still use the present tense if the situation was present/ongoing at that moment.

So:

• Я увидела, что наш поезд задерживается...

means that at the moment she looked, the train was currently being delayed / was showing as delayed.

In English, we often say:

• I saw that our train was delayed or
• I saw that our train was being delayed

Russian naturally keeps задерживается in the present because it describes the state as it appeared then.

Yes, it is the reflexive form, from задерживаться.

Here it means something like:

• is delayed
• is being delayed
• is running late

This is not truly reflexive in the English sense of it delays itself. Russian reflexive verbs often have meanings that are passive-like or intransitive.

Compare:

• задерживать поезд = to delay a train
• поезд задерживается = the train is delayed / is being delayed

So -ся here helps create the intransitive/passive-style meaning.

Because Russian uses на + accusative to show the amount of delay:

• задерживаться на пять минут
• опоздать на час
• перенести на неделю

So:

• на десять минут = by ten minutes / for ten minutes

The noun after на is in the accusative:

• десять минут

This expression is very common with time differences.

Because after на in this expression, you need the accusative, not the genitive.

Also, with numbers:

• одну минуту
• две / три / четыре минуты
• пять минут
• десять минут

So десять минут is the normal form here.

You would get десяти минут in other grammatical situations, for example with a preposition or case that requires it, but not in на десять минут.

Yes, but the nuance is slightly different.

• поезд задерживается = the train is delayed / is being delayed / is running late
• поезд задержан = the train has been delayed

Задерживается sounds very natural on station boards and in everyday speech when talking about the current situation.

Задержан is also correct, but it can sound a bit more formal or like an announced result.

No, Russian word order is fairly flexible, but this version is very natural.

Я посмотрела на табло и увидела, что наш поезд задерживается на десять минут.

This order is good because it follows the sequence of events:

1. looked at the board
2. noticed the information

You could rearrange parts for emphasis, but the original is the most neutral and natural.

For example:

• Я увидела, что наш поезд задерживается на десять минут, когда посмотрела на табло.

This is possible, but it feels differently structured and a bit less straightforward than the original.

Yes, in context it often can.

Literally, увидела means saw, but in sentences like this it often means:

• saw
• noticed
• realized from looking

So depending on the translation style, I looked at the board and realized that our train was delayed by ten minutes can be a perfectly good English rendering.

That does not change the Russian grammar; it is just a matter of choosing the most natural English wording.