Tôi nhắc cậu về lịch hẹn.

A word-by-word breakdown is:

• Tôi = I
• nhắc = remind, mention again, bring up
• cậu = you, in an informal or familiar way
• về = about, regarding
• lịch hẹn = appointment, scheduled meeting, appointment time

So the whole sentence means something like:

• I remind you about the appointment
• I’m reminding you about the appointment

The exact English wording depends on context, because Vietnamese does not mark tense the same way English does.

Vietnamese pronouns depend heavily on the relationship between speakers.

Cậu is a familiar, informal way to say you. It is often used:

• between friends
• to someone younger
• to someone of similar age in a casual relationship

It is not a general all-purpose you like in English.

Depending on the situation, you might also hear:

• bạn = neutral you
• anh = older brother / older male / you if the other person is an older male
• chị = older sister / older female / you if the other person is an older female
• em = younger person / you if the other person is younger

So cậu tells you something about the social relationship, not just the grammar.

Not equally. Cậu is understandable, but it has regional and social flavor.

In many learning materials, bạn is presented first because it is more neutral and widely usable.
So a more neutral version would be:

• Tôi nhắc bạn về lịch hẹn.

That said, cậu is perfectly natural in the right context, especially in informal speech.

In this sentence, nhắc most naturally means to remind.

But nhắc can also have a broader meaning like:

• mention
• bring up
• say again

For example, if someone says nhắc đến, it often means mention or bring up a topic.

In Tôi nhắc cậu về lịch hẹn, the structure strongly suggests remind someone about something, so remind is the best translation here.

Về means about or regarding.

So the pattern is:

• nhắc + someone + về + topic

In this sentence:

• cậu = the person being reminded
• về lịch hẹn = what the reminder is about

Without về, the sentence would sound less natural or less clear in this meaning.

So về is important because it introduces the topic of the reminder.

Because Vietnamese handles this differently from English.

In English, we often say:

• I remind you
• I say to you
• I give it to you

Vietnamese often places the person directly after the verb without a separate word like English to.

So:

• nhắc cậu = remind you

This is a normal Vietnamese pattern. You do not need an extra word before cậu.

Not exactly.

• lịch hẹn usually refers to an appointment schedule, booked appointment, or appointment time
• cuộc hẹn refers more directly to the meeting or date itself

In many everyday contexts, lịch hẹn can be translated simply as appointment.

Roughly:

• Tôi nhắc cậu về lịch hẹn. = I’m reminding you about the appointment
• Tôi nhắc cậu về cuộc hẹn. = I’m reminding you about the meeting/date/appointment itself

In real life, both can work depending on what you want to emphasize.

The structure is:

• Subject + verb + person + về + topic

So here:

• Tôi = subject
• nhắc = verb
• cậu = person receiving the reminder
• về lịch hẹn = topic of the reminder

You can use the same pattern in other sentences, for example:

• Tôi nhắc bạn về bài kiểm tra. = I remind you about the test
• Anh ấy nhắc tôi về cuộc họp. = He reminds me about the meeting

This is a very useful pattern to learn.

By itself, it has no fixed tense.

Vietnamese often leaves tense unmarked unless the context makes it clear. So Tôi nhắc cậu về lịch hẹn could mean:

• I remind you about the appointment
• I am reminding you about the appointment
• I’ll remind you about the appointment

depending on the situation.

If you want to make the time clearer, you can add time words or markers:

• Tôi đang nhắc cậu về lịch hẹn. = I am reminding you about the appointment
• Tôi đã nhắc cậu về lịch hẹn rồi. = I already reminded you about the appointment
• Tôi sẽ nhắc cậu về lịch hẹn. = I will remind you about the appointment

Yes, it is natural, especially in a straightforward spoken or written context.

However, in real conversation, Vietnamese speakers might also say slightly different versions depending on tone and situation, such as:

• Tôi nhắc cậu về cuộc hẹn nhé.
• Tớ nhắc cậu về lịch hẹn nhé.
• Mình nhắc bạn về lịch hẹn nhé.

Adding nhé makes it softer and friendlier.

So your sentence is fine, but everyday speech often adds particles or uses different pronouns.

A more neutral version is:

• Tôi nhắc bạn về lịch hẹn.

A more polite version depends on who you are speaking to:

• Em xin nhắc anh về lịch hẹn.
• Em xin nhắc chị về lịch hẹn.

These sound more respectful because Vietnamese politeness comes largely from pronoun choice and wording.

So if you are unsure, bạn is usually safer than cậu.

Yes, if the subject is obvious from context.

Vietnamese often omits subjects when they are already understood. For example, in conversation you might hear:

• Nhắc cậu về lịch hẹn nhé.

That could mean:

• I’m reminding you about the appointment, okay
• Just reminding you about the appointment

But when you are learning, keeping tôi in the sentence is helpful because it makes the structure clearer.

A few parts may be tricky for English speakers:

• nhắc has the nh sound, somewhat like the first part of the Spanish ñ sound, plus a short vowel and a sharp falling tone
• cậu has the ậ vowel, which is short and clipped
• hẹn has a heavy, creaky falling tone

The tones matter a lot. Even if your grammar is correct, wrong tones can make the word hard to understand.

If you are practicing, pay special attention to:

• nhắc
• cậu
• hẹn

Those are likely the hardest parts of the sentence for an English speaker.

Yes, in some contexts nhắc can be understood as mention or bring up. But in this sentence, the most likely reading is still remind.

That is because the pattern:

• nhắc ai về việc gì

usually sounds like reminding someone about something.

If you really wanted the meaning mention, other wording might be clearer, depending on context.

So for a learner, the safest interpretation here is:

• I remind you about the appointment