watasitati ha seizi no hanasi wo sita.

は marks 私たち as the topic of the sentence.

So 私たち は means something like as for us or more naturally in English, just we.

In this sentence:

• 私たち は = we
• 政治 の 話 を した = talked about politics

A key point: は is not exactly the same as an English subject marker. It marks what the sentence is about, which often becomes the subject in English.

Here, の links two nouns together.

• 政治 = politics
• 話 = talk, story, discussion

So 政治の話 literally means a talk/story/discussion of politics, and more naturally:

• a discussion about politics
• political talk
• talk about politics

In Japanese, noun + の + noun is a very common pattern. Depending on context, it can show:

• possession: 私の本 = my book
• category/type: 日本の車 = Japanese car
• content/topic: 政治の話 = talk about politics

Because 話 is being treated as the thing that was done.

The pattern is:

• 話をする = to have a talk / to talk / to discuss

So in this sentence:

• 政治の話をした = talked about politics / had a discussion about politics

Even though English uses the verb talk, Japanese often expresses this with the noun 話 plus the verb する.

So literally, it is closer to:

• did a discussion about politics

but the natural English translation is simply:

• we talked about politics

Both are possible, but they are not exactly the same structure.

1. 話をした

This uses:

• 話 = talk/discussion
• する = do

So it means to have a talk or to discuss.

2. 話した

This is the verb 話す in the past tense, meaning spoke or talked.

So:

• 政治の話をした = had a discussion about politics
• 政治について話した = talked about politics

Both can be natural.
The sentence you were given focuses a little more on the discussion/topic itself.

They are very similar, but the grammar is different.

政治の話をした

Literally: did political talk / had a discussion about politics

• 政治の話 is a noun phrase
• then をした means did / had

政治について話した

Literally: talked concerning politics

• 政治について = about politics
• 話した = talked

Both can be translated as talked about politics.

A small nuance:

• 政治の話をした can feel like we had a conversation/discussion on the topic of politics
• 政治について話した more directly means we spoke about politics

In many situations, the difference is small.

Because Japanese verbs usually come at the end of the sentence.

した is the past plain form of する.

• する = do
• した = did

So the sentence ends with the action, and the tense is shown there.

That means the whole sentence is in the past:

• 私たちは政治の話をした。
• We talked about politics.

Japanese does not usually mark past tense on every word. The final verb carries that information.

It can mean several related things, depending on context:

• story
• talk
• conversation
• discussion

In 政治の話, the most natural meaning is:

• talk about politics
• discussion of politics

It does not usually mean a fictional story here.
Because of the context and the use of をした, it clearly means some kind of conversation or discussion.

Yes, very often.

Japanese frequently leaves out subjects and topics when they are already clear from context.

So in a real conversation, someone might simply say:

• 政治の話をした。

That could still mean:

• We talked about politics
• I talked about politics
• They talked about politics

depending on context.

Including 私たち makes the subject/topic explicit: we.

It is in the plain style because it ends with した, not しました.

• した = plain past
• しました = polite past

So:

• 私たちは政治の話をした。 = plain style
• 私たちは政治の話をしました。 = polite style

The plain style is not automatically rude. It is commonly used:

• in casual conversation
• with friends/family
• in diary-style writing
• in narration
• in informal written Japanese

Usually yes, but it literally means we / us as a group including the speaker.

In this sentence, 私たちは is naturally we.

A useful detail: Japanese often does not have to state pronouns as much as English does. So when 私たち is included, it may be there for clarity, emphasis, or contrast.

For example:

• 私たちは政治の話をした。 = We talked about politics.

This can sound like we did, perhaps as opposed to someone else.

Japanese word order is more flexible than English, but particles are what show each word’s role.

In this sentence:

• 私たち
  • は = topic
• 政治の話
  • を = object
• した = verb

This order is very natural:

• 私たちは政治の話をした。

You may sometimes see variations for emphasis, but the standard learner-friendly order is topic + object + verb.

The important thing is that the particles tell you what each part is doing.

They are almost certainly just for learning.

Normal Japanese writing usually does not put spaces between words like this:

• 私たちは政治の話をした。

Learner materials often add spaces to make the sentence easier to read:

• 私たち　は　政治　の　話　を　した。

So the spaces are not part of standard Japanese grammar. They are just a reading aid.