رقم البنك في الرسالة.

Yes. In Arabic, present-tense sentences often leave out is/are.

So رقم البنك في الرسالة is understood as:

• رقم البنك = the bank’s number / the bank number
• في الرسالة = in the message

So the full sense is The bank’s number is in the message.

This is a very normal Arabic sentence pattern.

Literally, it means the number of the bank or the bank’s number.

This is an idafa construction (a possession/association structure):

• رقم = number
• البنك = the bank

When two nouns are put together like this, the first noun is connected to the second, often like of or apostrophe-s in English.

So:

• رقم البنك = the bank’s number
• literally: number the-bank

Because in an idafa construction, the first noun usually does not take الـ.

So Arabic says:

• رقم البنك

not:

• الرقم البنك

That second version would be incorrect.

Even without الـ on رقم, the whole phrase رقم البنك is still definite, because البنك is definite.

In Arabic idafa, definiteness comes from the second noun.

So:

• رقم بنك = a bank’s number / a bank number
• رقم البنك = the bank’s number

Because البنك has الـ, the whole phrase becomes definite.

This is one of the most important rules of Arabic noun phrases.

في means in.

الرسالة means the message, the letter, or sometimes the text/email/message, depending on context.

So في الرسالة literally means in the message or in the letter.

Because الرسالة has الـ, it refers to a specific message/letter, not just any message.

It can mean several related things, depending on context:

• letter
• message
• sometimes text message
• sometimes even email/message

In Egyptian Arabic, رسالة is often used very naturally for message in general.

So if the meaning shown to the learner is message, that is perfectly reasonable.

Not necessarily.

رقم البنك literally means the bank’s number or the number of the bank. Depending on context, that could mean a bank code, branch number, phone number, or something else connected to the bank.

If you specifically mean bank account number, Arabic more often says something like:

• رقم الحساب = the account number
• رقم الحساب البنكي = the bank account number

So learners should not automatically assume رقم البنك always means bank account number.

A natural Egyptian-style pronunciation would be roughly:

raʔm el-bank fir-risāla

A few notes:

• رقم is often pronounced raʔm in Egyptian, because ق often becomes a glottal stop ʔ
• البنك is el-bank
• الرسالة is pronounced er-risāla
• after في, you hear fir-risāla

A more careful or more standard-style pronunciation might keep the q sound in raqm.

Because ر is a sun letter.

When الـ comes before a sun letter, the l sound of الـ is absorbed into the next consonant.

So:

• written: الرسالة
• pronounced: er-risāla / ar-risāla depending on accent/style

In Egyptian Arabic, learners often hear this as er-risāla.

That is why في الرسالة is commonly heard as fir-risāla.

The wording works in both, but the writing is neutral enough to be understood as either Modern Standard Arabic or Egyptian Arabic.

The main difference is usually in pronunciation, not spelling:

• MSA: raqm al-bank fī ar-risālah
• Egyptian: raʔm el-bank fir-risāla

So an Egyptian learner can absolutely use this sentence, but should pronounce it in an Egyptian way if speaking colloquially.

Yes, in some contexts it could.

It could be understood as:

• The bank number is in the message — a full sentence

but without context, Arabic can sometimes also leave room for a phrase like:

• the bank number in the message

In your example, the period and the likely context make the full-sentence reading the most natural one.

So for a learner, the safest reading here is: The bank’s number is in the message.