Cô ấy rất khỏe.

A word-by-word breakdown is:

• cô = a woman, often a young woman; depending on context, it can also be aunt, miss, or a female teacher
• ấy = that; when used after a pronoun-like word, it helps mean that person / she / her
• rất = very
• khỏe = healthy, well, strong

So cô ấy means she in this sentence, and Cô ấy rất khỏe means She is very healthy / She is very well / She is very strong, depending on context.

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

In English, you say:

• She is healthy

In Vietnamese, you simply say:

• Cô ấy khỏe

To make it stronger:

• Cô ấy rất khỏe = She is very healthy

So the basic pattern is:

• subject + adverb + adjective

No separate is is needed here.

Not always. Cô ấy literally refers to that woman / that young woman, and in many contexts it is naturally translated as she.

However, cô is a relationship-based word, so its exact feeling depends on context. It can refer to:

• a young woman
• a woman slightly older than the speaker
• an aunt
• a female teacher

In this sentence, the natural translation is she, but the Vietnamese expression still carries a social sense that English usually does not show.

Vietnamese does not have just one simple pronoun that works exactly like English she in all situations. Instead, Vietnamese often uses kinship terms or social-role words.

Some possible words for she include:

• cô ấy
• chị ấy
• bà ấy
• cô ta
• cô ấy

The choice depends on age, relationship, politeness, and attitude.

So cô ấy suggests a particular kind of female referent, often a younger or middle-younger woman, depending on the speaker’s point of view.

Rất means very. It intensifies the adjective that follows it.

Examples:

• Cô ấy khỏe = She is healthy / well
• Cô ấy rất khỏe = She is very healthy / very well

So rất works much like English very.

It can mean all of those, depending on context.

Common meanings of khỏe include:

• healthy
• well
• strong
• in good condition physically

For example:

• Bạn có khỏe không? = Are you well?
• Anh ấy rất khỏe. = He is very strong / very healthy

In Cô ấy rất khỏe, the most natural meaning is usually She is very healthy or She is very well, but strong can also fit in the right context.

A rough pronunciation guide is:

• cô ≈ coh with a level tone
• ấy ≈ something like ay with a rising tone
• rất = pronunciation depends on dialect:
  • in northern Vietnamese, the r is often like a z sound
  • in southern Vietnamese, it may sound more like an English r
• khỏe ≈ khweh with a dipping/rising tone on khỏe

A rough overall guide might be:

• coh ay zat khweh in a northern-style approximation

But the tones are very important. If the tones are wrong, people may not understand you, even if the consonants and vowels are close.

The marks show both vowel quality and tone.

In this sentence:

• ô in cô shows a specific vowel sound
• ấ in ấy shows both the vowel shape and the tone
• ấ in rất does the same
• ỏe in khỏe includes a tone mark on ỏ

Vietnamese writing is very precise. These marks are not optional decorations—they change pronunciation and can change meaning.

So you should learn words together with their accent marks:

• co is not the same as cô
• khoe is not the same as khỏe

Yes. This is a very normal Vietnamese sentence pattern.

The structure is:

• Cô ấy = subject
• rất = degree word
• khỏe = adjective

So the order is:

• subject + degree word + adjective

This is very common in Vietnamese.

Other examples:

• Anh ấy rất cao. = He is very tall.
• Trời rất nóng. = The weather is very hot.

Yes. That is completely natural.

• Cô ấy khỏe. = She is healthy / She is well.
• Cô ấy rất khỏe. = She is very healthy / very well.

Adding rất simply makes the statement stronger.

In everyday speech, Vietnamese also often uses other intensifiers, such as:

• lắm
• quá

For example:

• Cô ấy khỏe lắm. = She is very healthy / very well.
• Cô ấy khỏe quá. = She is so healthy / so well.

Yes, often it can.

Vietnamese frequently drops subjects when they are already clear from context.

For example, if everyone knows you are talking about her, someone might just say:

• Rất khỏe.
• Khỏe lắm.

However, in a standalone textbook sentence, Cô ấy rất khỏe is clearer and more complete.

It is generally neutral and natural.

It is not especially formal, but it is also not slangy. The tone mainly depends on the pronoun choice:

• cô ấy sounds fairly neutral
• cô ta can sometimes sound more distant or slightly negative depending on context
• using a person’s name instead can sound more natural in some conversations

So Cô ấy rất khỏe is a good standard learning sentence.

Sometimes, yes, depending on context.

Because khỏe can suggest general physical strength or good health, She is fit may work in some situations. But khỏe is broader than English fit.

It often means:

• healthy
• well
• physically strong

If you specifically mean athletically fit, Vietnamese might use other expressions depending on the situation. So fit can be a possible translation, but not always the best one.