Nhờ nhân viên mà khẩu phần được chuẩn bị.

Nhờ ... mà ... is a common Vietnamese pattern meaning thanks to ... , ... or because of ... , ... with a usually positive result.

So:

• Nhờ nhân viên mà ... = Thanks to the staff / employees, ...
• Nhờ A mà B = Because of A, B happens

In this sentence, the speaker is saying that the preparation of the portions happens thanks to the staff.

In the pattern nhờ ... mà ..., mà connects the cause and the result.

• Nhờ nhân viên mà khẩu phần được chuẩn bị. = Thanks to the staff, the portions are prepared.

You can think of mà here as a structural linker rather than a word with a strong standalone meaning.

In natural English, we usually do not translate it directly. It just helps form the Vietnamese expression:

• Nhờ A mà B
• Vì A mà B
• Tại A mà B

So in this sentence, mà helps mark khẩu phần được chuẩn bị as the result.

Here, nhờ means thanks to or because of, not simply by.

That matters because:

• Nhờ nhân viên = thanks to the staff
• bởi nhân viên or just context-based passive interpretation would be closer to by the staff

So this sentence is not mainly focusing on the agent in a passive sentence. It is focusing on the helpful cause.

A natural interpretation is:

• Thanks to the staff, the portions are prepared.

not mainly:

• The portions are prepared by the staff.

Even though English may sometimes translate it that way depending on context, the Vietnamese sentence emphasizes the contribution of the staff.

Here được marks a passive-like structure.

• chuẩn bị = to prepare
• được chuẩn bị = to be prepared

So:

• khẩu phần được chuẩn bị = the portions are prepared

In many cases, được can also suggest a positive or favorable result, but in this sentence it is most naturally understood as a passive marker.

Compare:

• Nhân viên chuẩn bị khẩu phần. = The staff prepare the portions.

• Khẩu phần được chuẩn bị. = The portions are prepared.

Yes, at least the second part is passive or passive-like:

• khẩu phần được chuẩn bị = the portions are prepared

The full sentence combines:

1. a cause phrase: Nhờ nhân viên mà ...
2. a passive result: khẩu phần được chuẩn bị

So the whole sentence means something like:

• Thanks to the staff, the portions are prepared.

Vietnamese does not always use passive forms as often as English does, but được + verb is a very common way to express one.

By itself, nhân viên does not show singular or plural clearly.

It can mean:

• an employee
• employees
• staff

The exact meaning depends on context.

In this sentence, English speakers will often understand it as the staff or employees because that sounds more natural:

• Nhờ nhân viên mà ... = Thanks to the staff ...

If you want to make plurality clearer in Vietnamese, you could add words like:

• một nhân viên = one employee
• các nhân viên = the employees
• nhân viên đó = that employee / those employees, depending on context

Khẩu phần usually means portion, ration, or serving of food.

Depending on context, it could refer to:

• a meal portion
• a ration
• a serving size
• an allotted food portion

So khẩu phần được chuẩn bị is something like:

• the portions are prepared
• the meal portions are prepared
• the rations are prepared

If you were talking about meals in a more everyday way, Vietnamese might also use words like:

• bữa ăn = meal
• suất ăn = meal serving / set meal

But khẩu phần is perfectly possible when the focus is on the allocated portion of food.

Vietnamese does not use articles like English a, an, and the.

So:

• nhân viên could mean an employee, the employee, or employees
• khẩu phần could mean a portion, the portion, or portions

You decide the best English article from context.

That is why this sentence can be translated in more than one way:

• Thanks to the staff, the portions are prepared.
• Thanks to an employee, the meal portion is prepared.

The context tells you which one is most natural.

Sometimes yes, but nhờ ... mà ... is a very standard and clear pattern.

So:

• Nhờ nhân viên mà khẩu phần được chuẩn bị.
  sounds complete and structured.

A shorter version like:

• Nhờ nhân viên, khẩu phần được chuẩn bị.

may also be understood, but nhờ ... mà ... is the textbook pattern and usually sounds better when you want to clearly show cause → result.

Usually nhờ suggests a positive, helpful, or beneficial cause.

That is why it is often translated as thanks to.

For example:

• Nhờ bạn mà tôi xong việc. = Thanks to you, I finished the work.

If the cause is neutral or negative, Vietnamese more often uses words like:

• vì = because of
• do = due to
• tại = because of / owing to

So in your sentence, nhờ nhân viên suggests that the staff are being presented as a helpful reason the portions get prepared.

Yes. That would be a very natural active sentence:

• Nhân viên chuẩn bị khẩu phần. = The staff prepare the portions.

The difference is in focus:

• Nhân viên chuẩn bị khẩu phần. focuses on who does the action.

• Nhờ nhân viên mà khẩu phần được chuẩn bị. focuses on the helpful role of the staff and the resulting prepared portions.

So the original sentence is a little more about crediting the staff than just stating the action.

Yes, it is grammatical and understandable, but whether it sounds fully natural depends on context.

It sounds most natural in situations where you want to emphasize appreciation or contribution:

• Thanks to the staff, the portions are prepared.

In very everyday conversation, speakers might choose a simpler sentence, such as:

• Nhân viên đã chuẩn bị khẩu phần.
• Nhân viên chuẩn bị các khẩu phần rồi.

But the original sentence is still a good example of:

• nhờ ... mà ...
• passive được + verb

So it is especially useful for learning grammar.