Learn Hardcore German: Kannst du mir kurz erklären, worum es in diesem Film geht? - Can you briefly explain to me what this film is about?

Kannst du mir etwas erklären? – Can you explain something *to me?* (dative)
Kannst du mich erklären? – ungrammatical; you don’t “explain me”.

Therefore mir (dative: to me) is correct here, not mich (accusative: me as a direct object).

What does kurz mean here? Is it about time or physical length?

Here kurz means “briefly” or “in a few words”, not physically short.

So Kannst du mir kurz erklären … is like:

Can you briefly explain to me …?
Could you explain it to me quickly, just in short?

It does not necessarily mean right now this second; it mainly stresses that you’re asking for a short explanation, not a long, detailed one.

Why is it worum and not just was?

Worum literally comes from wo + rum/um and means “what (something) is about” / “what it concerns”.

Was would just mean “what”, without the idea of about.
English often says “what this film is about”, but German needs the preposition um there: worum (es geht).

So:

worum es in diesem Film geht ≈ what this film is about
was dieser Film ist would mean what this film is (a horror film, a comedy, etc.), which is different.

Why do Germans use geht to mean “is about”?

The expression es geht um … is a fixed phrase meaning “it’s about … / it concerns …”.

Examples:

Worum geht es in dem Buch? – What is the book about?
Es geht um Liebe und Verlust. – It’s about love and loss.

So in worum es in diesem Film geht, geht isn’t “goes” in the physical sense; it’s part of this idiomatic structure es geht um = to be about.

Why is the verb geht at the very end: … worum es in diesem Film geht?

Because worum es in diesem Film geht is a subordinate clause (an indirect question) introduced by worum.

In German:

In main clauses, the verb is in second position:
Dieser Film geht um einen Jungen.
In subordinate clauses, the finite verb goes to the end:
…, worum es in diesem Film geht.

So the pattern is:

Worum geht es in diesem Film? (direct question, verb second)
Kannst du mir erklären, worum es in diesem Film geht? (embedded question, verb at the end)

What is the function of es in worum es in diesem Film geht? Can I leave it out?

Here es is a dummy subject that belongs to the phrase es geht um … (it is about …).

Full form: Es geht in diesem Film um X.
Turned into an indirect question: … worum es in diesem Film geht.

You cannot drop es:

❌ worum in diesem Film geht – ungrammatical
✅ worum es in diesem Film geht – correct

German typically keeps this es when forming indirect questions from es geht um ….

Why is it in diesem Film and not in diesen Film?

The preposition in can take:

dative for location (where something is)
accusative for direction (where something is going to)

Here we’re talking about what happens in the film (as a location / context), not movement into it. So we use dative:

in diesem Film – dative singular (masculine Film → diesem)

In diesen Film (accusative) would mean into this film, which doesn’t fit here.

What’s the difference between Kannst du and Können Sie here?

Kannst du …? addresses one person you know well: a friend, family member, classmate, etc. It’s informal (du-form).
Können Sie …? addresses either one person formally or several people politely. It’s the polite/formal form.

So:

Kannst du mir kurz erklären, …? – to a friend.
Können Sie mir kurz erklären, …? – to your teacher, a stranger, or in a formal setting.

Both mean Can you briefly explain to me…, but the level of formality changes.

Could I also say Könntest du mir kurz erklären …? What’s the difference?

Yes, you can say:

Könntest du mir kurz erklären, worum es in diesem Film geht?

This uses the Konjunktiv II of können (könntest), which makes the request more polite / softer, similar to:

Could you briefly explain to me …?
vs.
Can you briefly explain to me …?

So kannst = neutral, friendly; könntest = a bit more tentative and polite.

Is the word order Kannst du mir kurz erklären fixed, or can I move kurz and mir around?

Some variation is possible, but not all orders sound equally natural.

Most natural:

Kannst du mir kurz erklären, … (standard) Less natural, but possible with special emphasis:
Kannst du kurz mir erklären, … (emphasis on mir)
Kannst du mir erklären, worum es in diesem Film kurz geht? – unusual and sounds odd; kurz almost always goes with erklären, not with geht here.

General tendencies:

Unstressed pronouns (mir) tend to stay early in the sentence.
Adverbs like kurz usually come before the main verb they modify (erklären).

Could I also say … worum der Film geht instead of … worum es in diesem Film geht?

Yes, you can, and it’s common:

Kannst du mir kurz erklären, worum der Film geht?

Differences:

worum der Film geht – shorter, very natural in speech.
worum es in diesem Film geht – a bit more explicit; can emphasize this specific film (e.g. in contrast to another one) and keeps the fixed phrase es geht (in diesem Film) um … more clearly visible.

Both are grammatically correct and idiomatic; the original is just slightly more explicit and formal-sounding.

What’s the nuance of erklären compared to sagen, erzählen, or beschreiben?

erklären = to explain → make something understandable, clarify.
- Erklär mir den Film. – Explain the film to me (make the plot/meaning clear).
sagen = to say / tell
- Sag mir, worum es geht. – Tell me what it’s about.
erzählen = to tell / narrate (often a story, events)
- Erzähl mir von dem Film. – Tell me about the film (maybe summarize the plot).
beschreiben = to describe
- Beschreib mir den Film. – Describe the film (style, scenes, atmosphere, etc.).

In your sentence, erklären emphasizes clarifying the content rather than just mentioning it or narrating the whole story.

Why is there a comma before worum?

In German, every subordinate clause is separated from the main clause by a comma.

Main clause: Kannst du mir kurz erklären
Subordinate clause (indirect question): worum es in diesem Film geht

So the comma marks the start of the embedded question. Similar structure:

Ich weiß nicht, worum es in diesem Film geht.
Kannst du sagen, wann der Film anfängt?

Why is the tense geht (present) and not something like ging (past)? The film is already made, after all.

German normally uses the present tense for the content of works (films, books, songs, etc.), even if they were created in the past.

So:

Worum geht es in diesem Film? – What is this film about? (standard)
Worum ging es in diesem Film? – What was that film about? (possible, but usually refers to a specific viewing in the past, or a conversation about it that’s over).

Your sentence uses present to describe the timeless content of the film, which is the default way to talk about stories and works of art.

How polite or casual does the whole sentence sound?

With du, the sentence is informal, suitable for friends, classmates, or family:
- Kannst du mir kurz erklären, worum es in diesem Film geht?

It sounds:

neutral and friendly,
not rude; adding kurz even makes it a bit considerate, because you signal you’re only asking for a brief explanation.

For a more formal context (teacher, stranger, colleague you don’t know well), you’d switch to Sie:

Können Sie mir kurz erklären, worum es in diesem Film geht?