kaigityuu ni denwa ga nattara, soto ni dete kudasai.

会議中 means during a meeting or in the middle of a meeting.

It is made from:

• 会議 = meeting
• 中 = middle / during / while in progress

So 会議中 is a very common pattern:

• 授業中 = during class
• 仕事中 = while working
• 食事中 = during a meal

Here, 会議中 describes the time when the phone might ring.

The に marks the time context for the action.

So 会議中に電話が鳴ったら means something like if the phone rings during the meeting.

With time expressions, に is often used to show when something happens. In this sentence, it connects during the meeting to the event the phone rings.

You may sometimes see 会議中、電話が鳴ったら... without に, especially in looser speech or writing, but 会議中に is very natural and clear.

Because 鳴る is an intransitive verb.

That means the thing making the sound is treated as the subject, not the direct object.

So:

• 電話が鳴る = the phone rings
• ベルが鳴る = the bell rings

The particle が marks 電話 as the thing that rings.

If you want a transitive version, you use a different verb:

• 電話を鳴らす = to make the phone ring

So in this sentence, the phone is not being actively rung by someone in the grammar of the sentence; it is simply ringing.

～たら is a very common way to say if or when.

Here, 鳴ったら means if/when it rings.

Why is it useful here?

• It sounds natural for a practical condition.
• It fits instructions well.
• It implies: once that happens, do the next thing.

So the structure is:

• 電話が鳴ったら = if/when the phone rings
• 外に出てください = please go outside

You could sometimes use other conditionals, but ～たら is especially common for instructions based on a specific event.

This is a very common point of confusion.

In ～たら, the past form does not necessarily mean past time in English. It marks that the first action is completed before the next action happens.

So:

• 鳴ったら literally works like when it has rung / once it rings

In natural English, we usually just say:

• If the phone rings...
• When the phone rings...

So the た in 鳴ったら is part of the grammar pattern, not a sign that the whole sentence is talking about the past.

It can feel like either, depending on context.

In this sentence, it means something like:

• If the phone rings, please step outside
• When the phone rings, please step outside

The difference in English is subtle:

• if emphasizes the condition
• when can sound more like the speaker expects it might happen

Japanese ～たら often covers both ideas. In a rule or instruction like this, English speakers often understand it as if that happens, then do this.

Because 出る often uses に to show the destination or resulting location.

So:

• 外に出る = go outside
• 部屋に入る = enter the room

Here, 外 is the place you move to, so に is used.

You may also see を with 出る, but that marks the place you are leaving:

• 部屋を出る = leave the room
• 教室を出る = leave the classroom

So compare:

• 部屋を出て、外に出る
  • leave the room and go outside

In your sentence, the focus is on the destination, so 外に is natural.

It is the て-form of 出る plus ください.

• 出る = to go out / leave
• 出て = te-form
• ください = please do

So:

• 出てください = please go out / please step outside

This is a polite request or instruction. It is not as blunt as a plain command like 出て！, but it is still direct enough for signs, rules, or workplace instructions.

Yes, it is polite.

～てください is a standard polite way to tell someone to do something. It is common in:

• instructions
• requests
• announcements
• workplace rules
• customer service language

That said, it is still an instruction, not a very soft personal favor. If someone wanted to sound softer, they might say something like:

• 外に出てもらえますか = could you go outside?
• 外に出ていただけますか = could you please go outside?

But for a rule during a meeting, 出てください is completely natural.

In this sentence, 電話が鳴る most naturally means the phone rings.

電話 can refer to:

• a telephone / phone
• a phone call, depending on context

But with 鳴る, the image is usually the device ringing.

If you specifically wanted to focus on receiving a call, Japanese might also use expressions like:

• 電話がかかってきたら = if a call comes in
• 着信があったら = if there is an incoming call

So here, 電話が鳴ったら is a simple, natural way to express the situation.

Japanese often leaves that kind of information unstated if it is clear from context.

So 電話が鳴ったら does not explicitly say:

• your phone
• my phone
• someone’s phone

In context, it usually means if your phone rings or if a phone rings during the meeting.

Japanese frequently omits subjects and possessives when they are obvious from the situation. English usually wants more explicit information, but Japanese often does not.

Japanese often puts the condition before the main action.

So the structure is:

• 会議中に電話が鳴ったら = if the phone rings during the meeting
• 外に出てください = please go outside

This order is very normal in Japanese because it sets up the situation first and then gives the response.

You could think of it as:

• As for the case where the phone rings during the meeting, please go outside.

That is one of the most common ways Japanese organizes this kind of sentence.

The comma helps separate the condition from the main instruction:

• 会議中に電話が鳴ったら、
• 外に出てください。

It makes the sentence easier to read.

Japanese commas are often more flexible than English commas. They are used to show pauses, improve clarity, and separate chunks of meaning. In this sentence, the comma clearly marks the break between:

1. the if/when part
2. the main request

No, standard Japanese normally does not use spaces between words like this.

Normally it would be written as:

会議中に電話が鳴ったら、外に出てください。

The spaces are usually added in teaching materials to make the parts easier for learners to see. They are not part of ordinary Japanese writing.