Tối nay, tôi sẽ về nhà muộn vì phải họp ở công ty.

Tối nay means tonight / this evening, and Vietnamese often puts a time expression near the beginning of the sentence to set the time frame first.

So:

• Tối nay = tonight
• tôi sẽ về nhà muộn... = I will come home late...

This is very natural in Vietnamese. English can do this too: Tonight, I’ll come home late...

Sẽ is a future marker. In this sentence, it works a lot like will in English.

• tôi sẽ về nhà muộn = I will come home late

Vietnamese verbs do not change form for tense, so words like sẽ help show time. Without sẽ, the sentence could sound more neutral or depend more on context.

For example:

• Tôi về nhà muộn = I come home late / I’m coming home late / I came home late, depending on context
• Tôi sẽ về nhà muộn = I will come home late

Về means to return / to go back, and nhà means home / house. Together, về nhà means go home / come home.

You can say just về if the destination is already understood, but về nhà is clearer and very common.

Compare:

• Tôi sẽ về muộn. = I’ll be back late.
• Tôi sẽ về nhà muộn. = I’ll come home late.

So nhà specifies where the person is returning.

In Vietnamese, words like muộn often come after the verb or verb phrase.

• về nhà muộn = come home late

This is normal Vietnamese word order:

• verb phrase first: về nhà
• description of time/manner/result after: muộn

So although English says come home late, Vietnamese also places muộn after the action phrase.

Vì means because.

It introduces the reason:

• vì phải họp ở công ty = because I have to attend a meeting at the company / because I have to have a meeting at work

So the structure is:

• main statement: Tối nay, tôi sẽ về nhà muộn
• reason: vì phải họp ở công ty

Phải means must / have to.

So:

• phải họp = have to attend a meeting / have to meet

It shows obligation or necessity.

In this sentence, the subject after vì is not repeated, but it is understood to still be tôi:

• vì (tôi) phải họp ở công ty

Vietnamese often leaves out repeated subjects when they are clear from context.

Here, họp is a verb meaning to have a meeting / to attend a meeting / to meet for work.

So:

• phải họp = have to attend a meeting

It usually refers to a formal or work-related meeting, not a casual meeting with friends.

For example:

• họp ở công ty = have a meeting at the company
• họp lớp = class reunion / class meeting
• họp phụ huynh = parents’ meeting

Ở here means at / in, and công ty means company.

So:

• ở công ty = at the company / at work

This tells us the location of the meeting.

You may also see tại công ty, which is a bit more formal. In everyday speech, ở công ty is very natural.

Sometimes yes, but it depends on context.

Vietnamese often omits pronouns when the subject is already obvious. So in conversation, someone might say:

• Tối nay sẽ về nhà muộn vì phải họp ở công ty.

This can sound natural if everyone already knows who is being talked about.

However, including tôi makes the sentence clearer and is especially helpful for learners.

No. Tôi is a neutral, polite way to say I, but Vietnamese pronouns change depending on age, relationship, and situation.

For example, a speaker might say:

• em if speaking to someone older
• anh if a man is speaking to someone younger
• chị if a woman is speaking to someone younger
• mình in some casual situations

So the same sentence could become:

• Tối nay em sẽ về nhà muộn vì phải họp ở công ty.
• Tối nay anh sẽ về nhà muộn vì phải họp ở công ty.

The grammar stays the same; only the pronoun changes.

They are very similar and often both mean late.

So this sentence could also be:

• Tối nay, tôi sẽ về nhà trễ vì phải họp ở công ty.

A rough guide:

• muộn is widely used and very standard
• trễ is also common, especially in southern Vietnamese

Both are correct in many situations.

The comma separates the time expression from the main clause:

• Tối nay, = Tonight,
• tôi sẽ về nhà muộn... = I will come home late...

This is similar to English punctuation. The comma is helpful and natural in writing, though in casual writing people may sometimes leave it out.

Yes, Vietnamese allows some flexibility, especially with time expressions and reason clauses.

For example, these are also natural:

• Tôi sẽ về nhà muộn tối nay vì phải họp ở công ty.
• Vì phải họp ở công ty, tối nay tôi sẽ về nhà muộn.

But Tối nay, tôi sẽ về nhà muộn vì phải họp ở công ty. is very clear and natural because it gives:

1. the time first
2. the main action
3. the reason

That order is especially common in everyday Vietnamese.