Learn Hardcore Dutch: De film is een verfilming van de roman die Anna leest. - The movie is a film adaptation of the novel that Anna is reading.

Verfilming literally means filming-into, but idiomatically it means film adaptation – a movie that is based on an existing work like a book, novel, or play.

So in:

De film is een verfilming van de roman…
→ De film = the specific movie being talked about
→ een verfilming van de roman = a film adaptation of the novel

You could paraphrase it as:

Deze film is de filmische bewerking van die roman.
(This movie is the film adaptation of that novel.)

Why is it de film and de roman, not het film or het roman?

Dutch nouns have grammatical gender. There are:

de-words (common gender)
het-words (neuter)

Both film and roman are de-words, so:

de film, een film
de roman, een roman

Using het film or het roman is grammatically wrong in standard Dutch.

Unfortunately, which nouns are de and which are het is mostly something you must memorize. Dictionaries always indicate this (e.g. de film (m), de roman (m)).

Why is it een verfilming van de roman and not something like een film van de roman?

In Dutch, een verfilming van de roman is the natural way to say a film adaptation of the novel.

verfilming van X = film adaptation of X
een film van X is usually understood as:
- a film by X (X is the director/creator), or
- a film from X in some other sense (from that studio, from that franchise, etc.)

So:

De film is een verfilming van de roman.
= The movie is an adaptation of the novel.

You could also say:

De film is gebaseerd op de roman.
(The film is based on the novel.)

But een film van de roman does not normally mean an adaptation of the novel and sounds wrong in this context.

Why is it die Anna leest and not dat Anna leest?

In relative clauses, Dutch chooses between die and dat based on the gender/number of the noun being referred to:

die
- for de-words (common gender, singular)
- for all plurals
dat
- for het-words (neuter, singular)

Here, the relative pronoun refers to roman:

roman is a de-word → die

So we say:

de roman die Anna leest
(the novel that Anna is reading)

If the noun were a het-word, we would use dat:

het boek dat Anna leest
(the book that Anna is reading)

Why does the verb leest come at the end of die Anna leest?

Dutch has different word order in:

main clauses: the finite verb is in second position (V2)
subordinate clauses (including relative clauses): the finite verb goes to the end

Compare:

Main clause: Anna leest de roman.
(Anna reads the novel.)
→ verb leest is in second position.
Relative clause: de roman die Anna leest
(the novel that Anna reads)
→ die Anna leest, with leest at the end.

In die Anna leest, die introduces a subordinate (relative) clause, so the verb leest must go to the end of that clause.

Could die Anna leest also mean “that Anna is reading right now,” or is it only a general/habitual meaning?

The Dutch present tense (leest) can express both:

Habitual/general:
- de roman die Anna elke avond leest
  (the novel that Anna reads every evening)
Currently ongoing:
- In many contexts, de roman die Anna leest can mean
  the novel that Anna is (currently) reading.

Context usually tells you which one is intended.

If you really want to emphasize the ongoing action, you can use the progressive:

de roman die Anna aan het lezen is
(the novel that Anna is in the middle of reading)

But in everyday language, die Anna leest is often enough to express the “is reading (now)” idea.

Why can’t you say van de roman wat Anna leest instead of van de roman die Anna leest?

In standard Dutch, wat is not used as a relative pronoun after a normal, specific noun like roman.

Basic rule:

Use die/dat after a specific noun:
- de roman die Anna leest
- het boek dat Anna leest
Use wat:
- after indefinite pronouns: iets, niets, alles, veel, weinig
  - Alles wat Anna leest, is interessant.
- after words like het enige, het laatste, etc.
- when referring to a whole clause:
  - Hij kwam te laat, wat jammer was.

So:

van de roman die Anna leest ✅
van de roman wat Anna leest ❌ in standard Dutch

Can I ever use dat here, as in van de roman dat Anna leest?

No, not in standard Dutch.

Since roman is a de-word, the correct relative pronoun is die:

van de roman die Anna leest ✅

Using dat in this context:

van de roman dat Anna leest ❌

is considered incorrect in standard language (though you may hear similar forms in some dialects or informal speech). For correct, neutral Dutch, follow:

de-word (singular) → die
het-word (singular) → dat
all plurals → die

Could you replace roman with boek, and what would change in the sentence?

Yes, you can replace roman with boek, but two things change:

Meaning nuance:
- roman = specifically a novel, a type of book.
- boek = book in general (could be a novel, textbook, biography, etc.)
Grammar (article + relative pronoun):
- roman is a de-word:
  - de roman die Anna leest
- boek is a het-word:
  - het boek dat Anna leest

So the whole sentence becomes:

De film is een verfilming van het boek dat Anna leest.
(The film is a film adaptation of the book that Anna is reading.)