Bạn hiểu phí này không?

It uses a very common Vietnamese yes/no question pattern:

subject + verb + object + không

So here:

• bạn = subject
• hiểu = verb
• phí này = object
• không = question marker

Vietnamese does not need do/does the way English does, and it does not change the word order to make a question.

In this sentence, không is being used to turn the statement into a yes/no question.

Compare:

• Bạn hiểu phí này. = You understand this fee.
• Bạn hiểu phí này không? = Do you understand this fee?

This is one of the most useful Vietnamese question patterns to learn.

Not necessarily. Both of these are possible:

• Bạn hiểu phí này không?
• Bạn có hiểu phí này không?

The version with có can sound a bit more explicit or complete, but the shorter version is also natural in speech. Vietnamese often allows this kind of omission when the meaning is still clear.

Bạn is a common and fairly neutral way to say you, especially:

• with friends
• with people around your age
• in teaching materials
• in general, neutral examples

However, Vietnamese pronouns depend a lot on age, relationship, and social context. In real life, people often use family-style pronouns such as anh, chị, em, cô, chú, and so on instead of bạn.

So bạn is correct here, but it is not the only possible word for you.

In Vietnamese, demonstratives usually come after the noun.

So:

• phí này = this fee
• cuốn sách này = this book
• người này = this person

This is different from English, where this comes before the noun.

Hiểu means to understand, to comprehend, or to grasp the meaning of something.

Biết usually means to know, to be aware of, or sometimes to know how.

So:

• hiểu = understand
• biết = know

In this sentence, hiểu suggests that the speaker is asking whether you grasp the fee, its meaning, or why it exists.

If you wanted to ask whether someone is simply aware of the fee, you might use a different sentence, such as:

• Bạn có biết về khoản phí này không?

Phí means fee or charge.

It is not exactly the same as:

• giá = price
• tiền = money, amount of money
• chi phí = cost/expense
• lệ phí = fee, often official or administrative
• học phí = tuition fee

So phí usually refers to a specific charge that someone has to pay.

It is understandable, but whether it sounds fully natural depends on the context.

If you are asking whether someone understands what a certain charge means, Vietnamese speakers might also say:

• Bạn có hiểu khoản phí này không?
• Bạn có hiểu phí này là gì không?
• Bạn có hiểu tại sao có phí này không?

Using just phí is possible, but khoản phí can sound a little more specific and natural when talking about a particular charge.

Not necessarily. Vietnamese does not always need a classifier in cases like this.

But you may also hear:

• khoản phí này

Here, khoản is often used for an amount, sum, or item of money, so khoản phí này can sound more precise.

So:

• phí này = fine and understandable
• khoản phí này = also common, often a bit more specific or formal

Some natural answers are:

• Có, tôi hiểu. = Yes, I understand.
• Vâng, tôi hiểu. = Yes, I understand.
• Không, tôi không hiểu. = No, I do not understand.
• Tôi chưa hiểu. = I don't understand yet.

Tôi chưa hiểu is especially useful because it sounds softer and more natural than a direct No in many situations.

The tones are:

• bạn = nặng tone
• hiểu = hỏi tone
• phí = sắc tone
• này = huyền tone
• không = ngang tone

A rough breakdown:

• bạn sounds short and heavy
• hiểu has a dipping-rising contour
• phí rises
• này falls
• không stays fairly level

Getting the tones right matters a lot in Vietnamese, especially for words like phí, because a different tone can create a different word or make you harder to understand.