Họ mua những sản phẩm này.

In this sentence, họ means they.

A few useful notes:

• họ is a third-person plural pronoun.
• It usually refers to a group of people.
• It does not usually refer to things the way English they sometimes can.
• Vietnamese often drops pronouns when the context is clear, but here họ is stated explicitly.

So:

• Họ mua những sản phẩm này. = They buy/bought these products.

Vietnamese word order here is basically:

• Họ = subject
• mua = verb
• những sản phẩm này = object

So the pattern is:

Subject + Verb + Object

That part is similar to English:

• They
  • buy
    • these products

Inside the object phrase, Vietnamese orders things differently from English:

• những = plural marker
• sản phẩm = noun
• này = this/these, placed after the noun

So:

• những sản phẩm này literally looks like plural product these

But natural English is:

• these products

những is a common plural marker. It tells you the noun is plural: products, not product.

So:

• sản phẩm này = this product
• những sản phẩm này = these products

Important nuance:

• những often suggests more than one, often some / several / a set of items.
• It does not work exactly like English the or some, but it helps mark plurality.

In this sentence, its main job is to show that sản phẩm is plural.

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

So:

• sản phẩm này = this product
• những sản phẩm này = these products

This is one of the most important word-order differences from English.

Compare:

• English: these products
• Vietnamese: những sản phẩm này

So if you want to say this/these + noun in Vietnamese, think:

noun + này

Yes, but the meaning changes.

• Họ mua sản phẩm này. = They buy/bought this product.
• Họ mua những sản phẩm này. = They buy/bought these products.

Without những, sản phẩm này is normally understood as singular: this product.

So if you want the clear plural meaning these products, keeping những is the normal choice.

It can mean either, depending on context.

Vietnamese verbs do not change form for tense the way English verbs do. The verb mua stays the same.

So:

• Họ mua những sản phẩm này. can mean
  
  • They buy these products
  • They bought these products
  • sometimes even They are buying these products, depending on context

If you want to make time clearer, Vietnamese often adds time words or markers:

• Họ đã mua những sản phẩm này. = They bought these products.
• Họ đang mua những sản phẩm này. = They are buying these products.
• Họ sẽ mua những sản phẩm này. = They will buy these products.

Because a classifier is not always required in Vietnamese.

With a noun like sản phẩm (product), the phrase những sản phẩm này is completely natural and standard.

A few helpful points:

• Vietnamese classifiers are common, but they are not used in every noun phrase.
• Formal or general nouns like sản phẩm, vấn đề, công ty, quốc gia often appear without a classifier in many contexts.
• In this sentence, những already marks plurality, and này marks these, so the phrase works perfectly without a classifier.

So learners should not expect every countable noun in Vietnamese to need a classifier every time.

Yes, you could also say:

• Họ mua các sản phẩm này.

Both are possible, but there is a nuance.

A simple way to think about it:

• những often feels like some / several / these plural items
• các often feels more general, categorical, or exhaustive, and can sound a bit more formal

In many everyday situations, both can be translated as plural. But:

• những sản phẩm này = these products / these particular products
• các sản phẩm này = also these products, but sometimes with a slightly broader or more formal feel

For many learners, the safest first takeaway is:

• những = common plural marker
• các = also plural, often more general or formal

Yes, sản phẩm is a normal and very common word for product.

It is especially common in:

• business
• advertising
• shopping
• product descriptions
• formal or semi-formal contexts

Examples:

• sản phẩm mới = new product
• chất lượng sản phẩm = product quality
• các sản phẩm chăm sóc da = skincare products

In very casual speech, people might sometimes use other nouns depending on the item, but sản phẩm itself is completely standard and natural.

Yes, Họ mua những sản phẩm này. is natural and grammatically correct.

It is a clear, standard sentence that works well for learners because it shows several common Vietnamese patterns:

• Subject + verb + object
• plural marker những
• noun sản phẩm
• demonstrative này placed after the noun
• no tense marking unless context or extra words are added

So it is a very useful model sentence.