Hộp này khá nhỏ.

• hộp = box
• này = this
• khá = quite, rather, fairly
• nhỏ = small

So the structure is basically:

hộp này = this box
khá nhỏ = quite small

In Vietnamese, demonstratives like này often come after the noun.

So:

• hộp này = this box
• nhà này = this house
• người này = this person

This is a very common pattern in Vietnamese. English says this box, but Vietnamese says box this.

Vietnamese often does not use a verb like to be when describing something with an adjective.

English:

• This box is quite small.

Vietnamese:

• Hộp này khá nhỏ.

The adjective nhỏ works directly as the predicate. This is very normal in Vietnamese.

Not exactly. Khá usually means quite, rather, or fairly. It makes the adjective stronger, but not as strong as very.

Compare:

• nhỏ = small
• khá nhỏ = quite/rather small
• rất nhỏ = very small
• hơi nhỏ = a little small / slightly small

So khá is somewhere in the middle.

A rough guide for English speakers:

• hộp ≈ hope but shorter, with a clipped final p, and with a heavy falling tone
• này ≈ nye or nai with a level-ish tone depending on dialect
• khá ≈ kha with an aspirated kh sound, like a strong k/h combination, and a rising tone
• nhỏ ≈ a bit like nyaw or nyo, with the nh sounding like Spanish ñ or the ny in canyon, plus a dipping/creaky tone

A few important sound notes:

• nh is not plain English n. It sounds like ny.
• kh is not just k. It has a breathy, aspirated quality.
• ộ and ỏ carry tones, and tones matter for meaning.

Yes. That is very natural.

• Hộp này khá nhỏ.
• Cái hộp này khá nhỏ.

Both can mean the same thing here: This box is quite small.

cái is a common classifier for many objects. In everyday speech, speakers often include it:

• cái hộp = a box / the box

But in short, simple sentences, the classifier is often omitted, especially when the meaning is already clear.

No, that sounds wrong.

In Vietnamese, degree words like khá, rất, and hơi usually come before the adjective.

Correct:

• Hộp này khá nhỏ.
• Hộp này rất nhỏ.
• Hộp này hơi nhỏ.

Not correct:

• Hộp này nhỏ khá.

So the pattern is:

noun + này + degree word + adjective

Yes, but the meaning changes.

• Hộp này khá nhỏ. = This box is quite small.
• Hộp khá nhỏ. = The box is quite small / A box is quite small, depending on context.

Without này, you lose the clear meaning of this.

A common way is to put không before the adjective:

• Hộp này không nhỏ. = This box is not small.

If you want to keep the idea of quite, you would usually rephrase depending on what you mean:

• Hộp này không nhỏ lắm. = This box is not very small.
• Hộp này không phải là nhỏ. = This box is not small.
  This is more emphatic or contrastive.

A natural yes-no question is:

• Hộp này khá nhỏ à? = Is this box quite small?
• Hộp này khá nhỏ hả? = Is this box quite small?
  This sounds conversational.

You can also ask more neutrally with context and intonation:

• Hộp này khá nhỏ?

Vietnamese often uses sentence-final particles like à, hả, or sao to show question tone.

Not necessarily. It depends on context.

khá nhỏ is fairly neutral by itself. It just says the box is on the small side. Whether that is good or bad depends on the situation:

• If you want something compact, khá nhỏ may be good.
• If you need more space, khá nhỏ may be a problem.

So the phrase describes size, not automatically approval or disapproval.

The sentence follows a very common Vietnamese pattern:

noun + demonstrative + degree word + adjective

In this case:

• hộp = noun
• này = demonstrative
• khá = degree word
• nhỏ = adjective

You can reuse this pattern easily:

• Nhà này khá đẹp. = This house is quite beautiful.
• Con mèo này khá to. = This cat is quite big.
• Cái bàn này khá cũ. = This table is quite old.