Preferisco vedere i film in lingua originale con i sottotitoli.

Preferisco is the 1st person singular form of preferire (to prefer): I prefer.

Many verbs ending in -ire take an extra -isc- in some present-tense forms. Preferire is one of them:

• io preferisco = I prefer
• tu preferisci = you prefer
• lui/lei preferisce = he/she prefers
• noi preferiamo = we prefer
• voi preferite = you all prefer
• loro preferiscono = they prefer

So preferisco is just the normal present-tense form for io.

After preferire, Italian often uses an infinitive when you are saying you prefer to do something.

So:

• Preferisco vedere... = I prefer to watch/see...
• Preferisco mangiare a casa. = I prefer to eat at home.
• Preferisco studiare la sera. = I prefer to study in the evening.

This works very much like English prefer to + verb.

Yes, you could also say Preferisco guardare i film... and it would sound natural.

Broadly speaking:

• vedere = to see, sometimes to watch
• guardare = to look at, to watch

With films, both are common.
In this sentence:

• Preferisco vedere i film... = I prefer to watch films...
• Preferisco guardare i film... = I prefer to watch films...

Guardare may feel slightly more explicitly like watching, but in everyday Italian both work well.

Italian often uses the definite article where English may leave it out.

So i film here means films / movies in general.

Compare:

• Mi piacciono i film italiani. = I like Italian films.
• Leggo i romanzi storici. = I read historical novels.
• Preferisco il caffè. = I prefer coffee.

In English, we often drop the article in general statements, but in Italian the article is usually needed.

Film is one of those nouns that usually stays the same in both singular and plural in Italian.

So:

• il film = the film
• i film = the films

The article tells you whether it is singular or plural.

Other borrowed words often behave like this too, though not all of them do.

In lingua originale is a very common expression meaning in the original language.

Here:

• in = in
• lingua = language
• originale = original

Italian often uses this phrase without an article in this context. It is a fixed, natural expression, especially when talking about films and series.

You will often see:

• un film in lingua originale
• guardare una serie in lingua originale

It means the audio is kept in the language it was originally made in.

It agrees with lingua, not with film.

The phrase is:

• lingua originale = original language

Since lingua is singular feminine, the adjective matches that noun.

So the structure is not original films, but rather films in original language.

That is why originale is singular here.

Both are possible in some contexts, but con i sottotitoli is the most straightforward and natural version here.

It literally means with the subtitles. In Italian, the article is often used in cases where English would just say with subtitles.

So:

• con i sottotitoli = with subtitles
• senza i sottotitoli = without subtitles

You may also hear con sottotitoli, especially in listings, menus, catalog descriptions, or more abbreviated language, but con i sottotitoli is very standard in a full sentence.

Because these parts of the sentence work differently.

• i film and i sottotitoli are nouns being referred to directly, and Italian normally uses the article with them here.
• in lingua originale is a set expression, where Italian usually does not use the article.

So this is not random. It is a combination of:

1. normal Italian article usage with plural nouns, and
2. an idiomatic phrase: in lingua originale.

Sottotitoli is the plural of sottotitolo.

• il sottotitolo = the subtitle
• i sottotitoli = the subtitles

It is a masculine noun:

• singular: -o
• plural: -i

So con i sottotitoli literally means with the subtitles.

The given order is the most natural neutral order:

• Preferisco vedere i film in lingua originale con i sottotitoli.

Italian word order is somewhat flexible, but not all changes sound equally natural.

For example, these are also possible depending on emphasis:

• Preferisco vedere i film con i sottotitoli in lingua originale.
• I film in lingua originale con i sottotitoli preferisco vederli.
  This is much more marked and emphatic.

For a learner, the original version is the best one to use.

Yes. In everyday Italian, film is the normal word for both film and movie.

So:

• un film can mean a film or a movie
• i film can mean films or movies

The exact English translation depends on the style of English you want:

• more neutral/international: films
• more everyday American English: movies

Grammatically, yes, but it is less standard in this context.

When talking about movies, shows, dubbing, and subtitles, Italian strongly prefers the set phrase:

• in lingua originale

That is the expression learners should remember and use. It is the most idiomatic choice here.