Learn Hardcore Czech: Dnes nemám čas dívat se na film. - Today I don't have time to watch a film.

Dnes nemám čas dívat se na film. – neutral, but with a slight emphasis on today (Today, I don’t have time…).
Nemám dnes čas dívat se na film. – neutral, with a slight emphasis on not having time today.

Czech word order is more flexible than English. Elements are moved mainly for emphasis and information structure, not for grammar. Putting dnes first is very natural because it sets the time frame at the start of the sentence.

Why is nemám written as one word? Is there a separate word for “not” like English not?

Czech negation is usually formed by adding ne- directly in front of the verb:

mám → nemám (I have → I don’t have)
chápu → nechápu (I understand → I don’t understand)
vidím → nevidím (I see → I don’t see)

So ne is a separate negative element historically, but in standard writing it’s attached to the verb as a prefix, not written as a separate word.

There is no equivalent of English auxiliary do (do not have); you just negate the main verb: mám → nemám.

Why is it mám čas dívat se and not something like “I have time for watching” with a noun?

Czech very often uses mít čas + infinitive:

mám čas jíst – I have time to eat
mám čas číst – I have time to read
nemám čas dívat se na film – I don’t have time to watch a film

You can make a noun phrase, e.g. mám čas na sledování filmu, but that sounds more formal and less natural in everyday speech. The infinitive construction (mít čas + infinitive) is the normal, conversational pattern.

What does se in dívat se mean? Can I just say dívat na film?

You cannot drop se here. The basic verb is dívat se (to watch, to look). It’s a reflexive verb that is practically always used with se.

dívat se na film – to watch a film
dívat se na televizi – to watch TV
dívat se z okna – to look out of the window

There is a form dívat without se, but it’s rare, old‑fashioned, or used only in special expressions. For normal “watching” or “looking”, always learn and use dívat se as a fixed unit.

Can I change the word order inside the phrase dívat se na film? For example, se dívat na film?

Yes, you will often see se dívat na film when the whole infinitive phrase moves somewhere:

Nemám čas se dívat na film.

Both:

Nemám čas dívat se na film.
Nemám čas se dívat na film.

are correct and natural.

Why the change?
se is a clitic (an unstressed little word) and tends to move toward the second position of the clause or phrase. Czech has fairly flexible rules for this, so both placements are possible and common here. As a learner, you can treat dívat se as a block but also be ready to see se dívat.

Why is it dívat se NA film and not some other preposition?

With dívat se in the sense of “watch / look at something”, Czech normally uses na:

dívat se na film – watch a film
dívat se na televizi – watch TV
dívat se na psa – look at the dog
dívat se na hodinky – look at the watch

In this use, na is roughly like English at in look at. You generally don’t use other prepositions here; dívat se + na + accusative is the standard pattern.

Why is it na film and not na filmu? What case is film in?

Here film is in the accusative case: na film.

The preposition na can take different cases depending on meaning:

na + accusative: direction, target, or object of attention
- jdu na film – I’m going to a film (to see it)
- dívám se na film – I’m watching a film
na + locative: location
- jsem na filmu is unusual, but e.g. jsem na koncertě – I’m at a concert

With dívat se na X (“watch X / look at X”), X is always accusative, so: na film, na psa, na televizi, etc., not na filmu.

Why isn’t there any word for “a” or “the” before film?

Czech has no articles (no equivalents of English a / an / the).

film can mean a film or the film, depending on context.
mám čas na film – I have time for a film / for the film (context decides).

The definiteness or indefiniteness that English expresses with articles is usually understood from context, word order, or other words, not from a special little word before the noun.

Does Dnes nemám čas dívat se na film mean only “I don’t have time right now”, or can it also mean the rest of the day?

In context, dnes normally means today (this whole day), not just this moment. So the natural interpretation is:

“I don’t have time today to watch a film” (at any point today).

Czech often uses the present tense for near future plans or lack of plans, especially with a time expression:

Zítra nemám čas. – I don’t have time tomorrow / I won’t have time tomorrow.
Dnes nemám čas dívat se na film. – I won’t have time today to watch a film.

So this sentence comfortably covers the rest of the day, not just the immediate present.

Could I say Dnes nemám čas na film instead? Is there any difference from dívat se na film?

Yes, Dnes nemám čas na film is correct and natural.

The nuance:

Dnes nemám čas dívat se na film. – focuses on the activity of watching a film.
Dnes nemám čas na film. – a bit shorter and more colloquial; treats film as an event/thing you don’t have time for.

In many real conversations, these two sentences would be used interchangeably. The version with dívat se is slightly more explicit about the action “to watch”.