هذا الفيلم مختلف عن الفيلم الذي شاهدناه أمس، لكن الموسيقى فيه جميلة.

In Modern Standard Arabic, a demonstrative like هذا often comes before the noun:

• هذا الفيلم = this film

This is the most standard neutral order in MSA.

A few useful points:

• هذا is used for a masculine singular noun.
• الفيلم is masculine singular, so هذا matches it.
• The noun after a demonstrative is usually definite, so it commonly takes ال:
  • هذا الفيلم
  • هذه القصة
  • هؤلاء الطلاب

In some varieties of spoken Arabic, you may hear the demonstrative after the noun, but in MSA, هذا الفيلم is the normal textbook pattern.

Because مختلف عن is the normal Arabic way to say different from.

So:

• مختلف عن الفيلم الآخر = different from the other film

This is a fixed pattern learners need to remember, just like English uses different from rather than different about in most cases.

Examples:

• هذا الكتاب مختلف عن ذاك الكتاب.
• رأيي مختلف عن رأيك.

So in your sentence:

• هذا الفيلم مختلف عن الفيلم... = This film is different from the film...

Arabic often repeats the noun explicitly where English might use a shorter structure.

Here, the phrase means:

• from the film that we watched yesterday

Arabic naturally says:

• عن الفيلم الذي شاهدناه أمس

This includes:

• الفيلم = the film
• الذي شاهدناه = that we watched

So the noun is repeated because the relative clause needs a clear noun before الذي.

In English, we can sometimes be looser, but in Arabic this full structure is very normal and natural.

الذي is a relative pronoun. Here it means that, which, or who depending on context.

In this sentence:

• الفيلم الذي شاهدناه أمس
• literally: the film that we watched yesterday

Why الذي?

Because الفيلم is:

• masculine
• singular
• definite

So Arabic uses الذي.

Some related forms are:

• التي for feminine singular
• اللذان / اللذين for masculine dual
• اللتان / اللتين for feminine dual
• الذين for masculine plural
• اللاتي / اللواتي for feminine plural

So if the noun were القصة, you would say:

• القصة التي قرأناها

شاهدناه can be split into three parts:

• شاهد = watched / saw
• نا = we
• ه = him / it

So:

• شاهدنا = we watched
• شاهدناه = we watched it

In this sentence, ه refers back to الفيلم.

So:

• الفيلم الذي شاهدناه أمس = the film that we watched yesterday

This is a very common Arabic pattern: a verb plus attached pronoun object.

More examples:

• قرأناه = we read it
• عرفته = I knew him/it
• سمعوها = they heard it if referring to a feminine noun

This is one of the most important things to notice in Arabic relative clauses.

In Arabic, the relative clause usually contains a resumptive pronoun that refers back to the noun being described.

So in:

• الفيلم الذي شاهدناه

the noun being described is الفيلم, and inside the clause you still get ه = it.

Literally, the structure is close to:

• the film that we watched it

That sounds wrong in English, but it is normal in Arabic.

This attached pronoun is very common and often required in Arabic relative clauses, especially when the noun being referred to is the object of the verb.

أمس means yesterday, and it often functions as an adverb of time by itself.

So:

• شاهدناه أمس = we watched it yesterday

You do not need a preposition like في here.

This is similar to English, where we say:

• I saw it yesterday not
• I saw it in yesterday

Also, أمس is commonly used without ال in this kind of sentence.

لكن means but.

It connects two ideas that contrast with each other:

• هذا الفيلم مختلف عن الفيلم الذي شاهدناه أمس
• لكن الموسيقى فيه جميلة

So the sentence says:

• This film is different from the film we watched yesterday, but the music in it is beautiful.

A useful note:

• لكن can act simply as but in standard writing.
• You may also learn لكنَّ with different grammar after it, but here the simple connective use of لكن is what matters.

فيه = في + ه

• في = in
• ه = him / it

So فيه means:

• in it

Here, it refers to the film.

So:

• الموسيقى فيه جميلة
• literally: the music in it is beautiful

This is a very common Arabic pattern: a preposition followed by an attached pronoun.

Examples:

• فيه = in it
• فيها = in it / in her for a feminine noun
• عليه = on it / on him
• معهم = with them

Both grammar and style are involved here.

The phrase:

• الموسيقى فيه جميلة

literally means:

• the music in it is beautiful

Arabic often places a phrase like فيه after the noun it describes:

• الموسيقى فيه = the music in it

This is very natural.

If you moved فيه, the emphasis and structure would change. The sentence as written is smooth and standard because it first introduces the music, then specifies in it.

Because it agrees with الموسيقى, and الموسيقى is treated as a feminine singular noun.

So:

• الموسيقى جميلة
• the music is beautiful

Adjectives in Arabic must agree with the noun they describe in gender and number.

Compare:

• الفيلم جميل = the film is beautiful
• الموسيقى جميلة = the music is beautiful

So جميلة is feminine singular to match الموسيقى.

Because most normal Arabic writing does not show short vowel endings.

In fully vocalized Arabic, the sentence could show endings such as:

• هذا الفيلمُ مختلفٌ عن الفيلمِ الذي شاهدناهُ أمسَ، لكن الموسيقى فيه جميلةٌ

But in everyday printed Arabic, newspapers, books, and most learning materials beyond the beginner stage, these endings are usually omitted.

So learners are expected to understand the grammar even when the case endings are not written.

It is mainly a nominal sentence because it begins with a noun phrase:

• هذا الفيلم

Then it gives information about it:

• مختلف عن الفيلم الذي شاهدناه أمس

The second part after لكن is also a nominal sentence:

• الموسيقى فيه جميلة

So the whole sentence contains two nominal clauses joined by لكن.

Even though there is a verb inside the relative clause:

• شاهدناه

that verb is only part of the description of الفيلم. It does not change the overall structure of the main sentence.