Rúguǒ jiāli méiyǒu rén, wǒ jiù qù yóujú qiānshōu bāoguǒ.

This is a very common Mandarin pattern for if... then... statements:

• 如果 ... ，就 ...

In this sentence:

• 如果家里没有人 = if there is no one at home
• 我就去邮局签收包裹 = then I’ll go to the post office to sign for the package

如果 introduces the condition, and 就 marks the result or next action.

English does not always need a separate word for then, but Mandarin often likes this pairing because it makes the relationship between the two parts very clear.

Yes, often it can.

You could say:

• 家里没有人，我就去邮局签收包裹。

This still sounds natural, especially in conversation, if the conditional meaning is already clear from context.

However, using 如果 makes the sentence more explicitly conditional and slightly more complete.

家里 literally means inside the home / at home.

• 家 = home, family, household
• 家里 = in the home, at home

In this sentence, 家里没有人 means there’s nobody at home or there’s nobody in the house.

You could sometimes use 家 in related expressions, but 家里 is very natural when talking about whether people are physically present in the home.

Because 有 is negated with 没有, not 不.

In Mandarin:

• 有 → 没有 for do not have / there is not / are not
• 不有 is not standard Mandarin

So:

• 家里没有人 = there is no one at home

This is one of the most important negation rules to remember:

• use 没(有) with 有
• do not use 不 with 有

This is a common Mandarin existence pattern:

• Place + 没有/有 + person/thing

So:

• 家里没有人 = At home, there is no one

Mandarin often puts the place first when saying that something exists or does not exist somewhere.

Compare:

• 桌子上有一本书。 = There is a book on the table.
• 房间里没有人。 = There is no one in the room.

So 家里没有人 follows a very standard structure.

Yes, you can, and it has a very similar meaning.

Compare:

• 如果家里没有人
• 如果没有人在家

Both mean if no one is at home.

The first version, 家里没有人, is especially common because it uses the standard place + 没有人 pattern.

The second version, 没有人在家, focuses a little more directly on people being at home.

Both are natural, but 家里没有人 is very smooth and idiomatic.

Here, 就 mainly marks the result in the conditional sentence: then.

So:

• 如果家里没有人，我就去... = If there’s no one at home, then I’ll go...

Sometimes 就 can also suggest something like in that case, then, or even a sense of immediacy depending on context. But in this sentence, its main job is to connect the result to the condition.

So the safest understanding here is simply:

• 就 = then / in that case

Because 就 usually goes before the main verb phrase of the result clause.

The structure is:

• 我就去邮局签收包裹

That is:

• subject + 就 + verb/action

So 就 comes after the subject 我 and before the action 去邮局签收包裹.

This is very normal word order in Mandarin.

签收 means to sign for and receive something, usually a delivery, parcel, or official item.

It is more specific than just 签名 or 签字, which mean to sign one’s name.

So:

• 签名 / 签字 = sign
• 签收 = sign for and accept receipt of something

In the context of packages, 签收包裹 is exactly the kind of wording you would expect.

Mandarin often links actions directly without needing extra words like to or for.

Here:

• 去邮局签收包裹

literally looks like:

• go post office sign-receive package

But naturally it means:

• go to the post office to sign for / pick up the package

This is a kind of serial verb structure, where one action leads into another:

• 去邮局 = go to the post office
• 签收包裹 = sign for the package

Mandarin often expresses purpose this way without adding a special marker.

包裹 specifically means parcel / package.

包 has many meanings, including:

• bag
• bundle
• package, in some contexts

But 包裹 is more precise when talking about mail or delivered parcels.

So in a postal context, 包裹 is a very natural choice.

邮局 literally means post office.

In real life, package pickup might happen at:

• a post office
• a courier office
• a delivery station

But the word 邮局 itself specifically means post office.

So if the package belongs to the regular postal system, this fits perfectly. If it were from a private courier, other words might be used instead.

Yes.

Mandarin does not have verb tense in the same way English does. Very often, future meaning is understood from context.

Here, the conditional structure makes the future meaning clear:

• 如果家里没有人，我就去邮局签收包裹。

This implies a future or planned response:

• If no one is home, then I’ll go...

You do not need a special future tense ending. Context does the work.

If you wanted, you could add words like 会 or 要, but they are not necessary here.

Here, 人 means people / anyone in the sense of someone being present.

So 没有人 means:

• there is nobody
• there isn’t anyone

It does not mean people in general here. It refers to whether any person is at home.

The comma separates the condition from the result:

• 如果家里没有人， = if there is no one at home,
• 我就去邮局签收包裹。 = then I’ll go to the post office to sign for the package.

This is very common in Chinese writing, especially with 如果...就... sentences. It helps the sentence read clearly and reflects a natural pause.