watasitati ha ki no dokuna kodomo wo tasuketa.

は is the topic marker. It tells you that 私たち is the thing the sentence is about: as for us, ...

So 私たちは is naturally translated as we here.

A learner often compares は and が:

• は = marks the topic
• が = often marks the grammatical subject with more focus or emphasis

In this sentence, は is the normal, neutral choice for we as the topic.

It can mean either, depending on the particle and the sentence.

Japanese pronouns do not change form the way English pronouns do:

• we / us in English
• 私たち in Japanese

The particle shows the role:

• 私たちは = we as topic
• 私たちが = we as subject
• 私たちを = us as object

So here, because of は, it is understood as we.

気の毒な is an adjective-like expression meaning something like:

• pitiful
• poor
• unfortunate
• someone you feel sorry for

So 気の毒な子供 means a pitiful child, a poor child, or an unfortunate child, depending on the translation.

A very important nuance: it does not mean the child is poisonous or literally toxic, even though 毒 by itself means poison. The whole expression 気の毒 is a set phrase.

Because 気の毒 behaves like a na-adjective.

When a na-adjective directly modifies a noun, you add な:

• 気の毒な子供
• 静かな部屋
• 有名な人

So the な is there because 気の毒 is describing 子供.

If it came at the end of the sentence instead, you would usually use だ or です instead:

• その子供は気の毒だ。
• その子供は気の毒です。

In this expression, it is best to treat 気の毒 as a fixed phrase.

So for learners, the safest approach is:

• memorize 気の毒 as one vocabulary item
• read it as きのどく
• understand it as pitiful / unfortunate / sorry

The の here is not something you should try to translate word-for-word as normal possession, like A's B.

を marks the direct object of the verb.

The verb 助けた means helped, and the thing being helped is 子供:

• 子供を助けた = helped the child / children

So:

• 私たちは = we
• 気の毒な子供を = the pitiful child / children
• 助けた = helped

The dictionary form is 助ける.

Here is the pattern:

• dictionary form: 助ける = to help
• past plain form: 助けた = helped

So 助けた is the plain past tense.

If you wanted the polite past form, it would be:

• 助けました

It could be either.

Japanese nouns often do not show singular vs plural clearly:

• 子供 can mean child
• 子供 can also mean children

The correct English translation depends on context.

So 気の毒な子供を助けた could mean:

• helped the pitiful child
• helped the pitiful children

If the original meaning shown to the learner already chooses one, that is probably based on context.

Yes, it is grammatically correct.

However, 気の毒な has a somewhat specific nuance: it means the child is unfortunate or someone people feel sorry for. It is not just a general positive description.

In everyday conversation, many people might also say かわいそうな子供 for poor/pitiful child. But 気の毒な子供 is still correct and understandable.

Those spaces are usually just for learning.

Normal Japanese writing would be: 私たちは気の毒な子供を助けた。

Japanese is normally written without spaces between words. Textbooks and beginner materials often add spaces to make the structure easier to see.

A natural reading is:

• 私たち → わたしたち
• は → pronounced わ
• 気の毒な → きのどくな
• 子供 → こども
• を → often pronounced お
• 助けた → たすけた

So the whole sentence is:

わたしたちは きのどくな こどもを たすけた。