Chiều mai, khi tôi rảnh, tôi sẽ mang ô đến nhà hàng xóm của Lan.

Chiều mai means tomorrow afternoon or sometimes tomorrow late in the day.

Vietnamese very often puts time expressions near the beginning of the sentence to set the time frame first. So starting with Chiều mai is completely natural.

You could move it later, but the version here sounds very normal:

• Chiều mai, khi tôi rảnh, tôi sẽ mang ô...

Vietnamese usually does not need a preposition before common time expressions.

So you can simply say:

• chiều mai = tomorrow afternoon
• ngày mai = tomorrow
• tuần sau = next week

If you want, you can sometimes add vào before a time phrase:

• Vào chiều mai...

But in this sentence, leaving it out is more natural and common.

Khi means when.

So:

• khi tôi rảnh = when I’m free

It introduces a time clause. Vietnamese can place that clause before or after the main clause, just like English can sometimes do:

• Chiều mai, khi tôi rảnh, tôi sẽ mang ô...
• Tôi sẽ mang ô..., khi tôi rảnh vào chiều mai.

The first version is much more natural here.

Because Vietnamese usually does not use a word like am/is/are before adjectives or states in this kind of sentence.

So:

• tôi rảnh = I am free
• tôi mệt = I am tired
• tôi vui = I am happy

The word rảnh is an adjective/state word, and it can directly follow the subject.

Using là here would be unnatural.

Each clause has its own subject:

• khi tôi rảnh = when I am free
• tôi sẽ mang ô... = I will bring the umbrella...

Repeating tôi makes the sentence clear and fully grammatical.

In some casual situations, Vietnamese can drop a repeated subject if the meaning is obvious, but here the full version with both tôi is very natural and standard.

Sẽ is a future marker. It often corresponds to will in English.

So:

• tôi sẽ mang ô = I will bring the umbrella

You do not always have to use sẽ in Vietnamese if the time is already clear from context, especially since chiều mai already shows future time. But sẽ makes the future meaning more explicit.

Compare:

• Chiều mai tôi mang ô... = tomorrow afternoon I bring/am bringing the umbrella
• Chiều mai tôi sẽ mang ô... = tomorrow afternoon I will bring the umbrella

The version with sẽ is clearer for a learner and very natural.

Mang means something like carry, take, or bring, depending on context.

Here it means bringing an object somewhere:

• mang ô đến... = bring/take an umbrella to...

Đem is often very similar, and in many contexts you could also say:

• tôi sẽ đem ô đến...

Both are natural. Very roughly:

• mang often emphasizes carrying something along
• đem often emphasizes taking/bringing something to a place

In real usage, they overlap a lot.

Đến means to, arrive at, or come to, depending on context.

In:

• mang ô đến nhà hàng xóm của Lan

it marks the destination:

• to Lan’s neighbor’s house

So the structure is:

• mang ô = bring an umbrella
• đến nhà... = to the house...

You may also hear tới in similar sentences. It is often interchangeable with đến.

Here it does not mean restaurant.

This is a very common point of confusion.

Break it like this:

• nhà = house
• hàng xóm = neighbor
• của Lan = of Lan

So:

• hàng xóm của Lan = Lan’s neighbor
• nhà hàng xóm của Lan = Lan’s neighbor’s house

Why not restaurant? Because nhà hàng as restaurant is a fixed compound:

• nhà hàng = restaurant

But in this sentence, the phrase boundary is different:

• nhà | hàng xóm của Lan not
• nhà hàng | xóm của Lan

So context and structure show that nhà means house here.

Của is a common possession marker, like of or the English apostrophe-s.

So:

• hàng xóm của Lan = Lan’s neighbor

Then the full phrase:

• nhà hàng xóm của Lan = the house of Lan’s neighbor

Vietnamese sometimes leaves out của in certain expressions, but here của makes the relationship clear and natural.

Vietnamese does not have articles that work like English a/an/the.

So:

• ô can mean an umbrella or the umbrella
• nhà hàng xóm của Lan can mean Lan’s neighbor’s house

Context tells you whether something is definite or indefinite.

That is very normal in Vietnamese, so learners should not expect every noun to have a separate word for the or a.