Cô ấy buộc tóc.

Here, cô ấy means she.

A few useful details:

• cô by itself is not always a simple pronoun. It can mean a young woman, aunt, or female teacher, depending on context.
• Adding ấy makes it mean that woman/girl, which often works like she in English.

So:

• cô = a woman / miss / aunt / teacher / I-you term depending on situation
• cô ấy = she

Because Vietnamese often leaves out possessives like my, your, or her when the owner is obvious, especially with body parts.

So Cô ấy buộc tóc naturally means she is tying her own hair.

This is very common in Vietnamese. You do not need to say tóc của cô ấy unless you want to be extra explicit or contrast it with someone else’s hair.

Compare:

• Cô ấy buộc tóc. = She ties her hair.
• Cô ấy buộc tóc của bé. = She ties the child’s hair.

Literally, buộc means to tie / fasten, and tóc means hair.

But in natural English, buộc tóc is often better understood as:

• tie her hair up
• put her hair up
• tie her hair back

It is a general expression for fastening the hair with something like a hair tie, ribbon, or band. It does not by itself tell you the exact style unless the context does.

No. Another very common verb is cột.

So you may hear both:

• buộc tóc
• cột tóc

Both can mean to tie up hair. In everyday speech, both are natural, though preference can vary by region or speaker.

Some related verbs are more specific:

• búi tóc = make hair into a bun
• tết tóc = braid hair

So buộc tóc is a general way to say the hair is being tied up.

Not by itself. Vietnamese often does not mark tense the way English does. The time usually comes from context or from extra words.

So Cô ấy buộc tóc could mean different things depending on the situation, such as:

• She ties her hair
• She is tying her hair
• She tied her hair

If you want to make the time/aspect clearer, you can add markers:

• Cô ấy đang buộc tóc. = She is tying her hair.
• Cô ấy đã buộc tóc. = She tied / has tied her hair.
• Cô ấy sẽ buộc tóc. = She will tie her hair.

Yes, it is very straightforward:

• Cô ấy = subject
• buộc = verb
• tóc = object

So the pattern is:

Subject + Verb + Object

That is one reason this sentence feels fairly easy for English speakers.

Because Vietnamese does not use articles the same way English does.

In English, you often need words like a, an, or the. In Vietnamese, a noun like tóc can stand on its own if the meaning is clear.

So tóc here is just hair, without needing an equivalent of the hair or her hair.

A simple pronunciation guide is:

• cô ≈ coh
• ấy ≈ ay with a rising tone
• buộc ≈ something like boo-uhk, ending sharply
• tóc ≈ tok with a rising tone

Tone-wise:

• cô: level tone
• ấy: rising tone
• buộc: heavy low tone
• tóc: rising tone

So the tones matter a lot. Even if your consonants and vowels are close, wrong tones can make the sentence sound unnatural or harder to understand.

In this sentence, tóc means hair in general, especially the hair on someone’s head.

Vietnamese does not force you to mark singular vs. plural in the same way English does. So tóc here is not about a single strand of hair. It refers to her hair as a whole.

That is why buộc tóc is understood as tying up her hair, not tying one hair.