kuuseki ga dekitara, madogawa no seki ni suwaritai desu.

It is read:

くうせき が できたら、まどがわ の せき に すわりたい です。

Word-by-word:

• 空席 = くうせき = vacant seat / empty seat
• できたら = if it becomes available / if one opens up
• 窓側 = まどがわ = window side
• 席 = せき = seat
• 座りたいです = すわりたいです = want to sit

A common reading point is 窓側: it is まどがわ, not まどかわ.

できる has several meanings in Japanese, not just can do.

Its core idea is often to come into existence, to be formed, or to appear. So in this sentence:

• 空席ができる literally means an empty seat comes into existence
• in natural English, that becomes a seat opens up or a seat becomes available

So 空席ができたら means:

• if a vacant seat opens up
• when a seat becomes available

This is a very natural use of できる.

Because 空席 is the thing that comes into existence or appears.

In 空席ができる:

• 空席 = the vacant seat
• が marks it as the subject of できる

So the structure is:

• 空席ができる = a vacant seat appears / becomes available

You would not normally use を here, because nothing is directly being acted on. The seat is not an object being created by someone in this sentence; it is the subject of the event.

～たら makes a conditional: if or when.

So:

• できる = to become available
• できたら = if it becomes available / when it becomes available

In this sentence, たら is very natural because the speaker is talking about a future situation and what they want to do after that happens.

A useful nuance:

• if = focusing on the condition
• when = focusing on the expected sequence

Japanese たら can cover both, depending on context.

Because 窓側 is being used as a noun-like modifier: window side.

To connect it to 席:

• 窓側 = window side
• の = links one noun to another
• 席 = seat

So:

• 窓側の席 = the seat on the window side / a window seat

This is a very common pattern:

• 日本の会社 = a Japanese company
• 駅の近く = near the station
• 窓側の席 = a seat by the window

Because 座る normally takes に for the place where someone sits.

So:

• 席に座る = sit in a seat
• いすに座る = sit on a chair
• そこに座る = sit there

In this sentence:

• 窓側の席に座りたいです = I want to sit in/by the window seat

For learners, this is worth memorizing as a pattern:

• ～に座る
• ～に座りたい

It is built from the verb 座る.

Step by step:

• dictionary form: 座る
• stem: 座り
• add たい: 座りたい = want to sit
• add です for politeness: 座りたいです

So ～たい is the standard way to say want to do ~ with your own actions.

Examples:

• 食べたいです = I want to eat
• 行きたいです = I want to go
• 座りたいです = I want to sit

Also, ～たい behaves grammatically a lot like an い-adjective, which is why です can follow it.

座りたいです is perfectly natural and polite in many everyday situations.

It directly expresses the speaker’s desire:

• I want to sit...

If you want to sound softer or less direct, you might say:

• 座りたいと思います = I think I’d like to sit...
• 座れたらいいなと思います = I think it would be nice if I could sit...

But there is nothing wrong with 座りたいです here. It is a normal polite form.

• 席 means seat
• 空席 means vacant seat / empty seat

So 空席 is a more specific kind of 席.

In this sentence:

• 空席ができたら talks about the situation of a seat becoming open
• 窓側の席に座りたいです says what kind of seat the speaker wants

A more direct alternative could be:

• 窓側の席が空いたら、そこに座りたいです。
  • If the window seat opens up, I want to sit there.

The original sentence is still natural, but it is a little broader in the first half and more specific in the second half.

Yes, and that is a very natural alternative.

Compare:

• 空席ができたら = if a vacant seat becomes available / if a seat opens up
• 席が空いたら = if a seat becomes empty / if a seat opens up

Both are natural, but the focus is slightly different:

• 空く focuses on something becoming empty
• できる focuses on a vacancy appearing / becoming available

In everyday conversation, 席が空いたら is probably the more common phrasing.

Japanese usually does not mark a/the the way English does.

So 窓側の席 could mean:

• a window seat
• the window seat
• a seat by the window

The exact meaning depends on context.

For example:

• On a train with many window seats, it may mean a window seat
• If there is one specific seat being discussed, it may mean the window seat

The same is true for number:

• 空席 could mean a vacant seat
• or just vacancy / open seat(s) depending on context

The sentence expresses the speaker’s personal preference in a polite, matter-of-fact way.

It sounds like:

• If a seat opens up, I’d like to sit in a window seat.

It is not:

• a command
• a request to another person
• a firm plan

It is simply stating a wish or intention, dependent on a condition.

So the overall tone is:

• polite
• natural
• not overly formal
• not pushy

Yes, it could be clearer to specify the window seat in the first clause, and Japanese often does that too.

For example:

• 窓側の席が空いたら、座りたいです。
  • If the window seat opens up, I want to sit there.

That version makes the target seat explicit right away.

The original sentence is still understandable, but it can sound a little like:

• If a seat opens up, I want to sit in a window seat

So the first half sets up the condition generally, and the second half gives the preference more specifically.

That kind of wording is not impossible in Japanese, but learners often notice that a more tightly matched version may feel clearer.