Cậu sẽ trực đêm.

You will keep watch at night.

Breakdown of Cậu sẽ trực đêm.

• sẽ: will
• cậu: you (informal, peer)
• trực đêm: to keep watch at night

Questions & Answers about Cậu sẽ trực đêm.

What does cậu mean here, and who can I use it with?

In this sentence, cậu is a pronoun meaning you, but it is not a neutral all-purpose you.

It is commonly used:

• between friends
• with someone around your age
• in familiar, casual relationships

It can sound natural if the speaker is talking to:

• a close friend
• a classmate
• a younger relative in some families

It is not the safest choice for every situation. Vietnamese pronouns depend heavily on age, relationship, and social context. In other situations, you might need:

• bạn
• anh
• chị
• em
• ông
• bà, etc.

So Cậu sẽ trực đêm. is natural only if cậu fits the relationship between speaker and listener.

What does sẽ do in the sentence?

Sẽ is a marker of future time. It usually means will or going to, depending on context.

So:

• Cậu sẽ trực đêm. = You will be on night duty.

Vietnamese does not conjugate verbs like English does, so words like sẽ help show time.

Compare:

• Cậu trực đêm. = You are on night duty / You do night duty / You’re on duty tonight, depending on context
• Cậu sẽ trực đêm. = You will be on night duty