القياس قبل البروفة.

A common Cairene-style pronunciation would be roughly:

el-ʔeyās abl el-borova

A few helpful notes:

• الـ is usually pronounced el- in Egyptian Arabic.
• ق often becomes a glottal stop ʔ in Cairo speech, so القياس sounds like el-ʔeyās.
• قبل is often pronounced abl in Egyptian.
• بروفة is commonly said something like borova; exact vowels can vary a bit by speaker.

Yes. In Arabic, especially in the present tense, you usually do not say a separate word for is/are.

So القياس قبل البروفة can naturally mean:

• The fitting is before the rehearsal
• or, depending on context, simply a short schedule-style statement

This is a normal kind of nominal sentence in Arabic.

Because الـ is the definite article, meaning the.

So:

• القياس = the fitting / the measuring
• البروفة = the rehearsal

English also allows two definite nouns in a sentence:

• The fitting is before the rehearsal

So there is nothing unusual about having الـ on both words.

Here you do pronounce it.

That is because both ق and ب are moon letters, not sun letters. So the article stays audible:

• القياس → el-ʔeyās
• البروفة → el-borova

If the next letter were a sun letter, the ل would assimilate, but that is not happening here.

قبل means before here.

It connects the first part of the sentence to the time reference that follows:

• قبل البروفة = before the rehearsal

You can think of it as functioning much like a preposition or adverbial time word.

A useful point for learners: Arabic does not need an extra word like of here. You simply say:

• قبل البروفة not
• قبل من البروفة

قياس is a noun, not a verb. More specifically, it is a verbal noun (often called a maṣdar).

That means it names the action or event itself, something like:

• measuring
• measurement
• fitting, depending on context

Arabic often uses verbal nouns where English might use either:

• a verb
• or an event noun

So instead of saying something like we measure before the rehearsal, Arabic may naturally use a noun phrase like the measuring / the fitting.

It is a loanword, but yes, it is a normal and very common word in Egyptian Arabic.

بروفة is widely used to mean:

• rehearsal
• trial run
• sometimes a practice session more generally

Even though it comes from a foreign source, it behaves like an Arabic noun in the sentence:

• it can take الـ
• it can come after قبل
• speakers use it very naturally

It is very easy to understand, but it feels more at home in Egyptian/colloquial usage because of بروفة, which is a common everyday word.

The basic structure itself is not strange at all and would be understandable more broadly. But:

• the sentence pattern is general Arabic
• the word بروفة feels colloquial and everyday
• the pronunciation like el-ʔeyās abl el-borova is specifically Egyptian

So you can think of it as a simple Arabic structure with a very Egyptian-flavored vocabulary/pronunciation.

You usually want to keep this order as the most neutral one:

القياس قبل البروفة

This is the straightforward way to say:

• The fitting is before the rehearsal

Arabic can sometimes move time phrases forward for emphasis, but for a learner, this version is the safest and most natural to use as a basic model.

So unless you have a special reason to emphasize before the rehearsal, stick with:

القياس قبل البروفة