wǒ búhuì yòng shǒujīyínháng.

Here, 不会 most naturally means don’t know how to.

In Mandarin, 会 + verb often means to know how to do something or to be able to do it because you learned it.

So:

• 我不会用手机银行。 = I don’t know how to use mobile banking.

This is different from:

• 我不能用手机银行。 = I can’t use mobile banking
  (for example, because the system is down, your phone is broken, or your account is blocked)

So 不会 focuses on lack of skill or know-how, not outside circumstances.

This is because of tone sandhi, a pronunciation change.

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

• 会 = huì (fourth tone)
• so 不会 is pronounced búhuì

This change is about pronunciation, not meaning.

No. In this sentence, 会 does not mean will.

会 has more than one meaning in Mandarin:

1. to know how to / can

   • 我会开车。 = I know how to drive.

2. will / be likely to

   • 明天会下雨。 = It will rain tomorrow.

In 我不会用手机银行, 会 is the first meaning: know how to / be able to because of learned skill.

用 means to use.

The structure is:

• 我 = I
• 不会 = don’t know how to / can’t
• 用 = use
• 手机银行 = mobile banking

So 不会用 means don’t know how to use.

You need 用 here because 手机银行 is a thing/service, and 用 is the verb that tells you what action is being done with it.

Usually, no. 我不会手机银行 sounds incomplete or unnatural.

That is because 手机银行 is a noun, not an action.
You need a verb to show what you can’t do with it:

• 我不会用手机银行。 = I don’t know how to use mobile banking.

Without 用, it sounds like 手机银行 is itself the action you don’t know how to do, which doesn’t work well in Mandarin.

手机银行 literally breaks down like this:

• 手机 = mobile phone / cellphone
• 银行 = bank

But together, 手机银行 means mobile banking or mobile banking services, often including a bank’s app or phone-based banking functions.

So it does not mean cellphone bank word-for-word in natural English. It refers to the service, not a physical bank.

The word order is:

Subject + modal/auxiliary + main verb + object

So:

• 我 = subject
• 不会 = modal-like element meaning don’t know how to / can’t
• 用 = main verb
• 手机银行 = object

Full pattern:

• 我不会用手机银行。

This is very normal Mandarin word order. It is similar to English:

• I don’t know how to use mobile banking.

Yes, 我不会用手机银行 is more natural and standard.

Why:

• 不会用 directly means don’t know how to use
• 不懂用 is less natural in this context

A very natural alternative would be:

• 我不懂怎么用手机银行。
  = I don’t understand how to use mobile banking.

So:

• 我不会用手机银行。 = very natural
• 我不懂怎么用手机银行。 = also natural
• 我不懂用手机银行。 = less natural

They all can relate to can’t, but they are used differently.

1. 不会

Used for lack of learned ability / not knowing how

• 我不会用手机银行。
  = I don’t know how to use mobile banking.

2. 不能

Used for inability due to conditions or must not

• 今天系统坏了，我不能用手机银行。
  = The system is broken today, so I can’t use mobile banking.

3. 不可以

Used for not allowed / not permitted

• 这里不可以拍照。
  = You may not take photos here.

So in your sentence, 不会 is the best choice because the issue is know-how, not permission or external conditions.

By itself, 我不会用手机银行 usually sounds like a general statement:

• I don’t know how to use mobile banking.

It describes your usual level of ability, not just a temporary problem at this moment.

If you want to emphasize a temporary situation, Mandarin would often use something else, for example:

• 我现在不能用手机银行。
  = I can’t use mobile banking right now.

So 不会 usually suggests an ongoing lack of skill or familiarity.

Not exactly. 不会用 is stronger than not good at. It usually means:

• don’t know how to use
• can’t use

If you want to say I’m not very good at using mobile banking, you could say:

• 我不太会用手机银行。
  = I’m not very good at using mobile banking / I don’t really know how to use it well.

Adding 不太 softens the sentence and makes it less absolute than 不会.