tā búhuì fēi.

This is because of a very common tone change rule in Mandarin.

• 不 is normally fourth tone: bù
• But when 不 comes before another fourth-tone syllable, it changes to second tone: bú

So:

• 不
  • 会 (huì) → 不会 (búhuì)

Since 会 is fourth tone, 不 changes from bù to bú.

So the sentence is pronounced:

• tā búhuì fēi

In this sentence, 会 means to know how to or to be able to because of learned ability.

So 不会飞 means:

• cannot fly
• doesn’t know how to fly
• is not able to fly

In other sentences, 会 can also mean other things, such as:

• will / future: 他会来。 = He will come.
• be likely to: 会下雨。 = It might rain.

But in 他不会飞, the meaning is about ability.

Both can sometimes be translated as cannot, but they are not exactly the same.

• 不会 usually means doesn’t know how to, or is not capable of
• 不能 usually means cannot because of circumstances, rules, or permission

Compare:

• 他不会飞。 = He can’t fly. / He doesn’t know how to fly.
• 他不能飞。 = He can’t fly right now / He isn’t allowed to fly / It’s not possible for him to fly.

So 不会飞 sounds like a lack of ability, while 不能飞 often sounds more like an external limitation.

In writing, 他 usually means he.

But in spoken Mandarin, 他, 她, and 它 are all pronounced tā.

So when you hear tā, you need context to know whether it means:

• he → 他
• she → 她
• it → 它

In this sentence, the written form 他 specifically means he.

There actually is one: 会.

Chinese often uses verbs like 会, 能, and 可以 where English uses can. In this sentence:

• 他 = he
• 不会 = cannot / doesn’t know how to
• 飞 = fly

So the structure is:

• subject + modal verb + main verb

That is why 不会 comes before 飞.

In Mandarin, modal verbs like 会, 能, and 可以 normally come before the main verb.

So the standard order is:

• subject + modal + verb

Examples:

• 他会说中文。 = He can speak Chinese.
• 我不能去。 = I can’t go.
• 你可以坐。 = You may sit.

So:

• 他不会飞 is correct
• 他飞不会 is not normal Mandarin word order

Not exactly.

• 他不会飞。 = He can’t fly. / He doesn’t know how to fly.
• 他不飞。 = He doesn’t fly.

不飞 usually describes a habit, choice, or action, not ability.

For example, 他不飞 could mean:

• he does not travel by plane
• he refuses to fly
• he isn’t flying

So if you want to talk about inability, 不会飞 is much better.

By itself, 飞 usually means to fly in the general sense.

So 他不会飞 normally means:

• he cannot fly

It usually sounds like he himself cannot fly, like a bird or superhero would.

If you want to say fly a plane, Chinese more often uses:

• 开飞机
• 驾驶飞机

For example:

• 他不会开飞机。 = He can’t fly a plane.

So 他不会飞 is usually not understood as He can’t pilot an aircraft.

No. 是 is not used here.

That is because 飞 is a verb, and 会 is a modal verb modifying it. Chinese does not use 是 before ordinary verbs the way English uses to be in some structures.

So:

• 他不会飞。 = correct
• 他是不会飞。 = possible only in special emphatic contexts, not as the basic sentence

For a simple statement, just use:

• 他不会飞。

The pronunciation is:

• tā búhuì fēi

Tone by tone:

• 他 tā — first tone
• 不 bú — second tone here because of tone change
• 会 huì — fourth tone
• 飞 fēi — first tone

A natural rhythm is:

• tā | búhuì | fēi

Try to keep 不会 together as one unit.

Usually, in this sentence, 不会飞 is understood as can’t fly or doesn’t know how to fly, not won’t fly.

If you want to say he won’t fly in the sense of refusal, Chinese would more naturally use something like:

• 他不肯飞。
• 他不愿意飞。

So:

• 不会飞 = cannot / doesn’t know how to fly
• 不愿意飞 = is unwilling to fly
• 不肯飞 = refuses to fly

Yes, often you can.

Chinese frequently drops the subject when it is obvious from context. So in conversation, if everyone already knows who you are talking about, you might just say:

• 不会飞。

But if you are introducing the idea clearly and fully, 他不会飞。 is the normal complete sentence.