رقمها في الرسالة.

It is رقم + ها:

• رقم = number
• ها = her

So رقمها literally means her number.

In Arabic, possessive pronouns are often attached directly to the noun, instead of using a separate word like her.

Because once a noun takes a possessive ending like -ها, it is already definite.

So:

• رقم = a number / number
• رقمها = her number

You do not say الرقمها. That would be wrong.

This is a very common Arabic pattern:

• كتاب = book
• كتابه = his book
• اسمها = her name

In Arabic, present-tense sentences like X is in Y often do not use a separate verb for is.

So رقمها في الرسالة literally looks like:

• her number
• in the message

But it naturally means Her number is in the message.

This is normal in both Standard Arabic and Egyptian Arabic.
If you wanted past tense, then a verb would appear, for example كان = was.

Yes. ها is the suffix for feminine singular possession or object.

So depending on context, رقمها can mean:

• her number
• its number for a feminine noun

In real conversation, context tells you which one is meant. In a sentence like this, it will often mean her number.

A common Egyptian pronunciation would be something like ra'amha fir-risāla.

A few useful notes:

• رقمها is often pronounced ra'amha in Cairo-style Egyptian, because ق is commonly pronounced like a glottal stop.
• الرسالة is pronounced er-risāla, because ر is a sun letter, so the l sound of ال assimilates.
• After في, people often say it smoothly as fir-risāla.

So you may hear:

• ra'amha fi r-risāla
• or more smoothly ra'amha fir-risāla

Both reflect the same sentence.

Because ر is one of the sun letters.

With sun letters, the ل of ال is not pronounced separately; instead, the following consonant is doubled.

So:

• written: الرسالة
• pronounced: er-risāla in Egyptian Arabic

This is the same kind of pattern as:

• الشمس → esh-shams
• الراجل → er-rāgil

So in your sentence, في الرسالة is written one way but pronounced with assimilation.

Not by itself. رقم literally means number in general.

But in everyday context, رقمها very often means her phone number, especially if people are talking about contacting someone.

So the exact meaning depends on context:

• mathematically: a number
• socially: often a phone number
• administratively: maybe an ID number, address number, etc.

If the meaning shown to the learner is her number, that is very likely the intended everyday meaning.

It can mean several things depending on context:

• message
• letter
• text message

In modern everyday Egyptian Arabic, رسالة can absolutely refer to a digital message too. So في الرسالة could mean:

• in the message
• in the text
• in the letter

Context decides which is most natural.

Yes, it is natural and understandable.

That said, Egyptian Arabic also has other common ways to talk about number, especially in speech. For example, some speakers may use نمرة in certain contexts.

So you may hear:

• رقمها في الرسالة
• or another colloquial wording depending on region and situation

But رقمها is completely normal and widely understood.

Yes, but رقمها في الرسالة is a very normal, neutral order.

It starts with the topic رقمها = her number, then gives the information في الرسالة = in the message.

Arabic can sometimes move parts of the sentence for emphasis, but for a learner, this version is the safest and most straightforward one to use.

So if you want to say Her number is in the message, this sentence is a good model.