المطر نزل امبارح بالليل.

A natural Egyptian pronunciation is:

il-maṭar nézel embāreḥ bil-lēl

A few notes:

• المطر → il-maṭar
  The ṭ is an emphatic t.
• نزل → nézel
• امبارح → embāreḥ
  The final ḥ is a stronger, breathier h sound.
• بالليل → bil-lēl
  The l is doubled in speech, so it sounds like bil-lēl, not bil-leyl with a clear break.

In Arabic, weather nouns are often used with the definite article, so المطر is the normal way to say rain in this kind of sentence.

So even though English says just rain, Egyptian Arabic often says the rain:

• المطر نزل = literally the rain came down
• natural meaning: it rained

Using مطر by itself here would sound less natural.

Because نزل literally means came down or went down, and that is a very natural way to talk about rain in Arabic.

So:

• المطر نزل = the rain came down
• idiomatically: it rained

This is one of those cases where Arabic uses a concrete verb and English uses a weather expression.

نزل is the past tense form.

More specifically, it is:

• 3rd person
• masculine
• singular
• past

It matches المطر, which is grammatically masculine singular.

So the sentence is talking about a completed event in the past: the rain fell last night.

Because Arabic does not need a dummy subject like English it in weather expressions.

English says:

• It rained

But the it does not really refer to anything.

Arabic usually names the thing directly:

• المطر نزل = the rain fell / it rained

So the sentence has a real subject, المطر, instead of a placeholder word.

Word by word:

• امبارح = yesterday
• بالليل = at night / during the night

Together, امبارح بالليل means:

• literally: yesterday at night
• naturally in English: last night

So this is a very common Egyptian way to say last night.

Here, بـ works like in, at, or during.

So:

• ليل = night
• الليل = the night
• بالليل = at night / during the night

This is a very common Egyptian structure for time expressions.

You may also hear في الليل, but بالليل is especially common in everyday speech.

Because two things are happening:

1. The preposition بـ attaches to the noun.
2. The ال of الليل merges with the ل because ل is a sun letter.

So:

• underlying form: ب + الليل
• spoken form: بالليل
• pronunciation: bil-lēl

That doubled l sound is completely normal.

By contrast, in المطر, the ل does not merge, because م is not a sun letter.

Yes. That is also natural.

Both of these are possible:

• المطر نزل امبارح بالليل
• نزل المطر امبارح بالليل

The difference is mostly about style and focus:

• المطر نزل... starts with the topic the rain
• نزل المطر... starts with the action fell / came down

In everyday Egyptian, both word orders are common.

The clearest clue is امبارح, which is colloquial Egyptian for yesterday.

In Modern Standard Arabic, you would expect something like:

• أمس
• البارحة

Also, the whole sentence has a very spoken, everyday feel. Egyptian Arabic prefers simple, conversational wording like this.

So:

• المطر نزل امبارح بالليل = very natural Egyptian speech
• a more formal version in Standard Arabic would be different in vocabulary and style

There are variants.

You may hear:

• امبارح
• مبارح

Both are common in speech, depending on the speaker and region.

For a learner, the important thing is to recognize that they refer to the same word: yesterday.

Because Egyptian Arabic very often expresses last night as:

• امبارح بالليل

Literally, that is yesterday at night, but it functions exactly like last night in English.

So even though English uses one compact expression, Egyptian commonly builds it from two parts:

• امبارح = yesterday
• بالليل = at night

That is one of the most normal ways to say it in conversation.