Cơ thể cần nghỉ.

• cơ thể = body
• cần = need / needs
• nghỉ = rest

So the structure is:

Subject + cần + verb

Literally: body + need + rest

That is why it can mean The body needs rest or The body needs to rest, depending on context.

In Vietnamese, you usually do not need a separate word like English to in needs to rest.

After cần, you can put a verb directly:

• cần nghỉ = need to rest
• cần ăn = need to eat
• cần ngủ = need to sleep

So cần nghỉ is completely normal Vietnamese structure.

Vietnamese does not use articles the way English does. There is no direct equivalent of the or a/an in most ordinary sentences.

So cơ thể can mean things like:

• the body
• a body
• one’s body / your body / the body in general

The exact meaning depends on context.

In a health context, Cơ thể cần nghỉ often feels like:

• The body needs rest
• Your body needs to rest

It behaves somewhat like both, depending on how you look at it.

In learner-friendly terms, it is easiest to treat cần as need and then put another verb after it:

• Tôi cần ngủ. = I need to sleep.
• Cơ thể cần nghỉ. = The body needs to rest.

So in this sentence, cần introduces what is needed, and nghỉ is the action.

They are very close, but not always identical in feel.

• nghỉ = rest / stop working / take a break
• nghỉ ngơi = rest, often with a slightly fuller sense of relax and recover

In many contexts, both work:

• Cơ thể cần nghỉ.
• Cơ thể cần nghỉ ngơi.

The version with nghỉ ngơi can sound a bit more complete or natural in health-related advice.
The shorter nghỉ is still understandable and natural enough, especially in simple statements.

Yes, it is understandable and natural enough, especially in a simple or direct style.

That said, depending on context, Vietnamese speakers might also say:

• Cơ thể cần nghỉ ngơi. = The body needs rest.
• Bạn cần nghỉ ngơi. = You need to rest.
• Cơ thể bạn cần nghỉ ngơi. = Your body needs rest.
• Cơ thể cần được nghỉ ngơi. = The body needs to be given rest.

So your sentence is fine, but in everyday conversation people may sometimes choose a slightly fuller version.

Vietnamese often leaves out information that is clear from context.

If a doctor is speaking to you, Cơ thể cần nghỉ can naturally imply:

• Your body needs rest
• Your body needs to rest

If you want to make it explicit, you can say:

• Cơ thể bạn cần nghỉ ngơi.

Here, bạn means your / you in this structure.

Vietnamese verbs do not change form for tense the way English verbs do.

So cần does not change like need / needed / will need, and nghỉ does not change like rest / rested.

Cơ thể cần nghỉ is usually understood as present or general truth:

• The body needs rest
• The body needs to rest

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

• Bây giờ cơ thể cần nghỉ. = The body needs rest now.
• Hôm qua cơ thể cần nghỉ. = The body needed rest yesterday.
• Ngày mai cơ thể sẽ cần nghỉ. = The body will need rest tomorrow.

Yes.

Vietnamese often uses a verb where English might use either:

• a noun phrase: needs rest
• or an infinitive phrase: needs to rest

So nghỉ is literally a verb, to rest, but English may translate the whole sentence in either way depending on what sounds more natural.

A rough learner-friendly guide is:

• cơ thể ≈ guh thê
• cần ≈ guhn
• nghỉ ≈ nghee? with a creaky, broken-rising tone

More carefully:

• cơ has the ơ vowel, which does not exist exactly in English
• thể has the hỏi tone
• cần has the huyền tone
• nghỉ has the ngã tone in standard northern pronunciation

A very important point: tones matter a lot, especially on thể, cần, and nghỉ.

Both can mean body.

• cơ thể is very common and neutral
• thân thể is also correct, but can sound a bit more formal or literary depending on context

For everyday health-related speech, cơ thể is very common and natural.

Yes, but the meaning changes a little.

• cần nghỉ = needs to rest
• phải nghỉ = must rest / has to rest

So phải is stronger and more forceful.

Compare:

• Cơ thể cần nghỉ. = The body needs rest.
• Cơ thể phải nghỉ. = The body must rest.

You do not need được here.

được can appear in sentences like:

• Cơ thể cần được nghỉ ngơi.

This literally feels more like:

• The body needs to be rested
• The body needs to be given rest

That version is a bit more formal or elaborate.

Your original sentence, Cơ thể cần nghỉ, is shorter and more direct.

Yes, and that is normal.

Vietnamese often allows body parts or the body itself to be the grammatical subject:

• Mắt cần nghỉ. = The eyes need rest.
• Não cần nghỉ ngơi. = The brain needs rest.
• Cơ thể cần nghỉ. = The body needs rest.

English sometimes prefers You need to rest, but Vietnamese is perfectly comfortable making the body the subject.

A very useful pattern is:

[thing/person] + cần + [verb]

Examples:

• Tôi cần ăn. = I need to eat.
• Bạn cần ngủ. = You need to sleep.
• Cơ thể cần nghỉ. = The body needs to rest.

You can also use:

[thing/person] + cần + [noun]

For example:

• Cơ thể cần nước. = The body needs water.

So cần can be followed by either a verb or a noun, depending on what is needed.