kaigisitu no howaitoboodo ni yotei wo kakikonde okeba, minna ga sugu kakunin dekiru.

Here, の links two nouns and shows that the second noun belongs to, is associated with, or is located in the first noun.

So:

• 会議室のホワイトボード = the whiteboard in the meeting room / the meeting room’s whiteboard

This is one of the most common uses of の in Japanese: noun + の + noun.

The に marks the place where something is written.

In this sentence:

• ホワイトボードに予定を書く = write the schedule on the whiteboard

With verbs like 書く and 書き込む, に often marks the surface or destination where the writing goes.

Compare:

• 紙に書く = write on paper
• ノートに書く = write in a notebook
• ホワイトボードに書く = write on a whiteboard

書く simply means to write.

書き込む adds the nuance of writing something into a space, entering it in, or filling it in. It often suggests writing something where it is meant to be recorded.

So:

• 予定を書く = write the schedule
• 予定を書き込む = write the schedule in / fill in the schedule / enter the schedule

In this sentence, 書き込む sounds natural because a whiteboard is being used as a shared place to record information.

〜ておく means to do something in advance or to do something and leave it that way for later convenience.

So:

• 書き込んでおく = write it down beforehand
• prepare it by writing it down

It often implies that the action is done now so it will be useful later.

Examples:

• 予約しておく = make a reservation in advance
• ドアを開けておく = leave the door open
• メモしておく = make a note for later

In your sentence, the idea is that writing the schedule on the whiteboard ahead of time will help everyone later.

Because the sentence is not just saying if you write it. It is saying if you write it down beforehand / if you make sure it is written there in advance.

Compare:

• 書き込めば = if you write it in
• 書き込んでおけば = if you write it in beforehand / if you have it written in advance

So 〜ておけば adds the important nuance of preparation.

This is a very common pattern:

• Vておく = do in advance
• Vておけば = if you do it in advance / if you have done it beforehand

It is built in steps:

1. 書き込む
2. Te-form: 書き込んで
3. Add おく: 書き込んでおく
4. Conditional ば form of おく: おけば
5. Combined: 書き込んでおけば

So the structure is:

• verb in て-form + おく + ば

Meaning:

• if you do X in advance

Both are possible in some contexts, but が fits well here because it marks who is able to do the action.

• みんながすぐ確認できる = everyone can quickly check it

With できる, the thing or person connected to the ability often gets focus with が.

Using は would sound more like setting everyone up as the topic for contrast, such as:

• みんなはすぐ確認できる = as for everyone, they can check it quickly

That is not impossible, but が sounds more neutral and natural in this sentence.

確認する means to check.
確認できる means can check / be able to check.

The sentence is emphasizing the result or benefit of writing the schedule on the whiteboard:

• if it is written there in advance, everyone will be able to check it quickly

So できる shows possibility / ease / ability.

It is not just saying everyone checks it, but that the whiteboard makes checking easy and possible.

すぐ means right away, immediately, or quickly depending on context.

Here it modifies 確認できる:

• すぐ確認できる = can check it right away

It shows that putting the schedule on the whiteboard makes the information easy to access without delay.

Japanese often omits subjects when they are obvious or unimportant.

In this sentence, the focus is on the general idea:

• If [someone/you/we] write the schedule on the whiteboard in advance, everyone can check it quickly.

The person doing the writing does not need to be stated. Depending on context, it could mean:

• if you write it down
• if we write it down
• if someone writes it down

This kind of omission is very normal in Japanese.

予定 is a broad word. It can mean:

• schedule
• plans
• appointments
• what is planned

So 予定を書き込む could mean writing:

• a schedule for the day
• upcoming plans
• meeting times
• who will use the room, etc.

The exact meaning depends on context. On a whiteboard in a meeting room, it often suggests a schedule or planned events.

Yes, you could, and it would still be natural.

Difference in nuance:

• 予定を書いておけば = if you write the schedule down in advance
• 予定を書き込んでおけば = if you write/fill the schedule in on the board in advance

書き込む feels a little more specific and practical, as if entering information into a shared record or designated space. 書く is more general.

Yes. 〜ば is one of the Japanese conditional forms and here it means if.

• 書き込んでおけば、みんながすぐ確認できる。
• If you write it down in advance, everyone can check it quickly.

This use of 〜ば often sounds logical or consequence-based:

• if X is done, then Y becomes possible

It fits well because the sentence expresses a practical result: writing the schedule in advance leads to easier checking.

Yes, in a grammatical sense.

• 確認する = to confirm / check
• 確認できる = can confirm / can check

This is the potential form built from the する verb pattern:

• する → できる
• so 確認する → 確認できる

Many noun + する verbs work this way:

• 利用する → 利用できる = can use
• 参加する → 参加できる = can participate
• 説明する → 説明できる = can explain

The sentence breaks down like this:

• 会議室のホワイトボードに = on the meeting room whiteboard
• 予定を書き込んでおけば = if you write the schedule in advance
• みんなが = everyone
• すぐ = quickly / right away
• 確認できる = can check it

So the structure is:

• [place] に [object] を [verbておけば], [result]

More abstractly:

• If X is done beforehand, Y becomes easy/possible.

This is a very common and useful Japanese sentence pattern.