Trọng lượng của bưu kiện khá lớn.

Vietnamese often leaves out the verb to be when an adjective directly describes something.

So:

• Trọng lượng của bưu kiện khá lớn. = The weight of the package is quite large.

Here, lớn works like the predicate adjective, and Vietnamese does not need a separate word like is before it.

A very common pattern is:

• Noun + adjective
• Căn phòng rộng. = The room is spacious.
• Thời tiết đẹp. = The weather is nice.

So this sentence is completely normal Vietnamese grammar.

Của marks possession or association, similar to of in English.

• trọng lượng của bưu kiện = the weight of the package

You can think of it as connecting two nouns:

• trọng lượng = weight
• bưu kiện = package / parcel
• trọng lượng của bưu kiện = the package’s weight / the weight of the package

It is very common in Vietnamese when you want to clearly show a relationship between two nouns.

Sometimes yes, but it changes the feel.

• Trọng lượng của bưu kiện khá lớn sounds natural, clear, and neutral.
• Trọng lượng bưu kiện khá lớn sounds more compressed, technical, or headline-like.

In everyday learning, it is safer to keep của here.

So for most learners, the best version is:

• Trọng lượng của bưu kiện khá lớn.

Khá means something like quite, rather, or fairly.

So:

• lớn = large
• khá lớn = quite large / rather large

It softens the statement compared with rất.

Compare:

• lớn = large
• khá lớn = quite large
• rất lớn = very large

So khá suggests a noticeable degree, but not an extreme one.

This is a very good question.

• nặng means heavy
• lớn means big/large

But when the subject is trọng lượng (weight), Vietnamese often uses lớn:

• Trọng lượng khá lớn = The weight is quite large.

If you talk about the package itself, then nặng is more natural:

• Bưu kiện khá nặng. = The package is quite heavy.

So the difference is:

• trọng lượng ... lớn = the weight is large
• bưu kiện ... nặng = the package is heavy

Both are natural, but they focus on different things.

Both can relate to weight/mass, but they are not always used in exactly the same way.

• trọng lượng usually corresponds to weight
• khối lượng usually corresponds more closely to mass, though in everyday Vietnamese it is also often used where English says weight

In daily life, people may use both in practical contexts like shipping, product labels, or measurements. But in more precise or scientific language:

• trọng lượng = weight
• khối lượng = mass

In your sentence, trọng lượng của bưu kiện is perfectly natural for talking about how heavy the parcel is in a shipping context.

Bưu kiện is a common and useful word, especially in postal, delivery, and shipping contexts. It means parcel or package.

It can sound a little more specific or official than some everyday alternatives.

Compare:

• bưu kiện = parcel, postal package
• gói hàng = package, parcel, shipment
• kiện hàng = package / shipment unit
• bưu phẩm = postal item, mail item

So bưu kiện is very appropriate if you are talking about mailing, delivery services, or shipping information.

The structure is:

• Trọng lượng = subject
• của bưu kiện = noun phrase modifying the subject
• khá lớn = predicate adjective phrase

So the overall pattern is:

• [Noun phrase] + [degree word + adjective]

More literally:

• Trọng lượng của bưu kiện = the weight of the package
• khá lớn = quite large

This kind of structure is extremely common in Vietnamese.

A very natural simpler version would be:

• Bưu kiện khá nặng. = The package is quite heavy.

This is shorter and more conversational.

Your original sentence is still correct, but it sounds a bit more formal or informational, as if describing a shipping detail or specification.

So:

• Trọng lượng của bưu kiện khá lớn. = slightly more formal / descriptive
• Bưu kiện khá nặng. = simpler and more everyday

A learner will usually want to pay attention to the tones:

• trọng — heavy dot tone
• lượng — falling-rising tone
• của — falling-rising tone
• bưu — level tone
• kiện — heavy dot tone
• khá — rising tone
• lớn — creaky/broken rising tone

A rough pronunciation guide:

• trọng lượng ≈ chawng lwuhng
• của ≈ koo-uh
• bưu kiện ≈ byoo kee-uhn
• khá lớn ≈ kha lawn

These are only rough approximations. The tones matter a lot, especially in words like lớn, kiện, and trọng.

A very common yes/no question pattern in Vietnamese is:

• Có ... không?

So you can say:

• Trọng lượng của bưu kiện có khá lớn không?

However, in natural speech, people might more often ask:

• Bưu kiện này có nặng không? = Is this package heavy?
• Trọng lượng của bưu kiện là bao nhiêu? = What is the weight of the package?

The first one is more everyday. The second asks for the actual number.

Usually khá is fairly neutral. It just indicates a moderate degree.

Depending on context, it can sound:

• mildly positive: khá tốt = quite good
• mildly negative: khá đắt = quite expensive
• neutral/descriptive: khá lớn = quite large

In your sentence, khá lớn is neutral and descriptive. It simply says the package’s weight is on the larger side.