Learn Hardcore Hungarian: Ma a városban sehol nincs csend. - Today there is no silence anywhere in the city.

Using nem van here would sound incorrect or at best very marked and unusual. For basic sentences of existence like this, always use nincs, not nem van.

What exactly does sehol mean, and why is it used with nincs?

Sehol literally means “nowhere / at no place” and comes from hol (where) with the negative particle se- (similar to sem).

Hungarian uses negative concord: when you have a negative word like sehol, you also use a negative verb form (here nincs):

sehol = nowhere
nincs = is not / there is not
→ sehol nincs = there is nowhere / nowhere is there

So Ma a városban sehol nincs csend. literally has “nowhere” and a negative verb, but in Hungarian that’s normal; it does not cancel out to a positive the way it might in English.

Why does városban have the article a, but csend has no article?

A városban has the definite article because we’re talking about a specific, known city in context – usually “in the city (we both know which one)”.

a város = the city
városban = in (a) city, in a city (no article)
a városban = in the city

Csend is an abstract, uncountable noun (“silence”), and in a general statement like this Hungarian often leaves it without an article:

nincs csend ≈ there is no silence / it is not quiet (in general)
nincs a csend would sound very odd here and would suggest some very specific “the silence”, which is not intended.

So: a városban is specific and gets an article; csend is an abstract, non-specific state and does not.

What does the ending -ban in városban mean?

The suffix -ban / -ben is the inessive case, meaning “in, inside”.

város = city
városban = in the city

Which form you use depends on vowel harmony:

back vowels → -ban (e.g. városban, házban)
front vowels → -ben (e.g. szobában actually uses -ban because of a back vowel, but kertben, hídben etc.)

So a városban simply encodes the preposition in the city inside the word.

Is this word order fixed, or can I move words around?

The word order is not completely fixed, but changing it changes the emphasis.

Original: Ma a városban sehol nincs csend.
Focus is on sehol (“nowhere in the city”).

Other possible orders (all grammatical, but with slightly different focus):

Ma sehol nincs csend a városban. – puts sehol even closer to the verb; still “Nowhere is there silence in the city today.”
Sehol nincs ma csend a városban. – stronger emphasis on sehol and then on ma; “Nowhere is there silence today in the city.”
A városban ma sehol nincs csend. – starts from the location, then adds time, then focus on “nowhere”.

In Hungarian, the focused element normally stands right before the verb (nincs here), so if you move something into that slot, you change what is being highlighted.

Why is there ma alone and not something like ma van?

Ma is an adverb meaning “today”, so by itself it can function as a time adverbial:

Ma a városban sehol nincs csend. – Today, there is nowhere silence in the city.

You only use van with ma in specific structures, e.g.:

Ma van péntek. – Today is Friday.
Ma van a születésnapom. – Today is my birthday.

Here we are not saying what “today is”; we’re just specifying when something happens. So ma alone as a time word is correct; no van is needed.

What’s the difference between sehol nincs csend and sehol sincs csend?

Both are correct and very close in meaning.

sehol nincs csend – nowhere is there silence
sehol sincs csend – nowhere is there even silence / there isn’t silence anywhere at all

The -s- in sincs comes from sem (“not even”), so sincs is historically sem + nincs.
In practice:

sehol nincs csend – neutral “nowhere is silent”
sehol sincs csend – a bit more emphatic, “nowhere is silent at all / not even in one place”

In everyday speech, sehol sincs csend might sound a bit more natural or expressive.

Why is csend a noun here instead of using an adjective like “quiet”?

In Hungarian, csend is a noun (“silence”), and the adjective meaning “quiet/silent” is csendes.

Hungarian very often describes the atmosphere of a place with a noun + van/nincs:

Csend van. – There is silence. / It is quiet.
Nincs csend. – There is no silence. / It is not quiet.

English usually uses an adjective (“it’s quiet / it isn’t quiet”), but Hungarian likes this “there is silence / there is no silence” structure with a noun. So Ma a városban sehol nincs csend. follows this common pattern.

Could I say Ma a város sehol nem csendes instead? Is that the same?

You can say Ma a város sehol nem csendes., and it is grammatical, but the nuance is slightly different.

nincs csend – focuses on the state of silence as a thing that is (not) present.
nem csendes – uses the adjective “quiet” to describe the city (or its parts).

So:

Ma a városban sehol nincs csend. – Today, in the city, there is no silence anywhere. (emphasis on the lack of silence as a state)
Ma a város sehol nem csendes. – Today, the city is not quiet anywhere. (emphasis more on the city’s areas not being quiet)

In meaning they’re very close and often interchangeable in casual speech, but the original puts more weight on “silence” as a noun.

Why is it nincs here and not nincsen or nincsenek?

All of these relate to van (“there is / is”), but they’re used differently:

nincs – standard short form, 3rd person singular
nincsen – a slightly longer, more emphatic or stylistic variant of nincs
nincsenek – plural form (for plural countable nouns)

In this sentence, csend is:

singular
uncountable (an abstract mass-like noun)

So the natural choice is:

nincs csend
or, slightly more emphatic / formal:
nincsen csend

You cannot use nincsenek here, because that needs a plural subject:

Nincsenek virágok. – There are no flowers. (plural)
Nincs csend. – There is no silence. (singular/uncountable)

Isn’t sehol nincs a “double negative”? Why doesn’t it turn the meaning positive?

In Hungarian, using more than one negative element does not turn the sentence positive. Instead, it is the normal way to express negation and often makes it stronger.

sehol – negative word (“nowhere”)
nincs – negative verb form (“there is not”)

Together: sehol nincs = “there is nowhere / nowhere is there”.

This is called negative concord: all the relevant words in a negative sentence show negation. English mostly avoids this (“I don’t see anything”, not “I don’t see nothing” in standard English), but Hungarian requires it.