minna ha heiwa ni tuite hanasimasita.

は marks みんな as the topic of the sentence.

So みんなは means something like as for everyone or everyone, ....

In this sentence, the speaker is telling us what everyone did:

• みんなは = as for everyone
• 平和について話しました = talked about peace

A learner might expect が, but は is very common when introducing what the sentence is about. が would sound more like you are specifically identifying everyone as the ones who talked, often in contrast with someone else.

みんな usually means everyone or everybody.

Even though it refers to multiple people, Japanese nouns do not have to show singular/plural the way English does. So みんな already naturally gives the idea of a group.

Depending on context, みんな can mean:

• everyone
• all of us
• you all
• all of them

In this sentence, it most naturally means everyone.

について means about, concerning, or regarding.

So:

• 平和について = about peace

It is a very common pattern for introducing a topic of discussion, study, writing, thought, and so on.

Examples:

• 日本について勉強する = study about Japan
• その問題について考える = think about that problem

In your sentence, 平和について話しました means talked about peace.

The に is part of the fixed grammar pattern ～について.

This expression comes from the verb つく in older usage, but for learners, the most useful thing is to remember ～について as one set phrase meaning about or regarding.

So it is best learned as:

• noun + について

Examples:

• 歴史について = about history
• 学校について = about school
• 平和について = about peace

Because 話す usually does not take the thing being discussed with を in this way.

To say talk about peace, Japanese normally uses:

• 平和について話す
• 平和のことを話す

So:

• 平和について話しました = talked about peace
• 平和のことを話しました = talked about peace

平和を話しました sounds unnatural.

A useful pattern to remember is:

• 人と話す = talk with a person
• 内容について話す = talk about a topic

Yes, 平和のことを話しました is also possible.

Both mean talked about peace, but there is a slight difference in feel:

• 平和について話しました sounds a bit more formal, organized, or topic-focused.
• 平和のことを話しました sounds a bit more conversational and direct.

In many situations, either one works.

The dictionary form is 話す.

Here is the breakdown:

• 話す = to speak / to talk
• 話しました = talked / spoke

話しました is the polite past form.

So the sentence is polite and refers to a completed action in the past.

Because ました marks polite past tense.

So:

• 話します = talk / will talk
• 話しました = talked

This tells us that the conversation already happened.

If you changed the sentence to:

• みんなは平和について話します。

it would mean something like:

• Everyone talks about peace or
• Everyone will talk about peace

depending on context.

It is polite, but not extremely formal.

The clue is 話しました, which uses the ます form. This is standard polite Japanese.

Compare:

• 話した = casual plain form
• 話しました = polite form

So:

• みんなは平和について話した。 = casual
• みんなは平和について話しました。 = polite

Yes. Japanese word order is more flexible than English, as long as the particles stay attached to the right words.

The most neutral order here is:

• みんなは平和について話しました。

But you could also say:

• 平和についてみんなは話しました。

This gives more emphasis to 平和について.

The verb usually comes at the end, but other parts can move around for focus or style.

No. Normally, Japanese is written without spaces:

• みんなは平和について話しました。

The spaced version is often used only in beginner materials to make the sentence easier to read:

• みんな　は　平和　に　ついて　話しました。

Also, in normal writing, について would not be separated into に　ついて. It is usually treated as one grammar unit.

A natural pronunciation would be close to:

• Minna wa heiwa ni tsuite hanashimashita

A few pronunciation notes:

• みんな = min-na
• は is written ha but pronounced wa when it is a particle
• 平和 = heiwa
• について = ni tsuite
• 話しました = hanashimashita

So although you see は, you say wa here:

• みんなは = minna wa

平和 means peace.

It can refer to:

• the absence of war
• harmony in society
• a peaceful state or condition

In this sentence, it is being treated as the topic everyone talked about.

Because Japanese does not use articles like a or the in the same way English does, 平和 can simply mean peace without needing an article.

Yes, very often.

Japanese frequently leaves out subjects or topics when they are understood from context. So in a conversation, someone might simply say:

• 平和について話しました。

That could still mean We talked about peace, They talked about peace, or even Everyone talked about peace, depending on context.

In your sentence, みんなは is included to make it explicit that everyone is the topic.