Learn Hardcore Czech: Večerní procházka v parku je pro moji rodinu důležitá. - An evening walk in the park is important for my family.

It belongs to the adjective type like cizí, jarní (often called the -í type), which has the same form for masculine, feminine, and neuter in the nominative singular.

So you get:

večerní procházka – evening walk (feminine)
večerní film – evening film (masculine)
večerní jídlo – evening meal (neuter)

The word does agree in gender, number, and case with the noun, but for this adjective type the nominative singular looks the same for all genders, so you don’t see the change on the surface.

Why is it procházka and not procházku?

Procházka (walk) is the subject of the sentence, so it is in the nominative case:

Večerní procházka v parku – An evening walk in the park (subject)
je – is
pro moji rodinu důležitá – important for my family (predicate)

If procházka were an object of a verb (in the accusative), you would use procházku, e.g.:

Mám rád večerní procházku v parku. – I like an evening walk in the park.

So: subject → nominative → procházka,
direct object → accusative → procházku.

What case is v parku, and why does park change to parku?

V parku is in the locative case (6th case), used mainly after certain prepositions to express location (where something is).

Base form (nominative): park
Locative singular (with v = in): v parku – in the park

Many masculine nouns ending in a consonant use -u in the locative singular:

v domě / v domovu / v domku (patterns vary)
v obchodě
v parku

With the preposition v:

v + locative usually means in, inside something:
- v parku – in the park
- v bytě – in the flat
- v Praze – in Prague

Why is it pro moji rodinu? What case is that, and how does pro work?

The preposition pro always takes the accusative case and usually means for (in favour of / for the benefit of).

Base form: rodina – family (nominative)
Accusative singular: rodinu
With pro: pro rodinu – for (a/the) family

Since the phrase is “for my family”, you need:

pro
- accusative
rodinu (accusative singular)
a matching possessive: moji (accusative feminine singular)

So pro moji rodinu = for my family.

Why moji and not moje or mou in pro moji rodinu?

The possessive můj (my) is irregular and has several forms for feminine singular:

Nominative: moje / má – moje rodina (my family – subject)
Accusative: moji / mou – vidím moji/mou rodinu (I see my family)

After pro, we need the accusative, so feminine singular accusative of můj is:

moji (very common in everyday speech)
mou (more formal/literary or stylistic choice)

So:

pro moji rodinu – fully natural, everyday style
pro mou rodinu – correct, a bit more formal/literary

Moje would be nominative here and is wrong in pro moje rodinu.

Why does důležitá end in -á here?

Důležitá is an adjective meaning important, and it must agree with the subject in gender, number, and case.

The subject is procházka:

procházka – feminine, singular, nominative

So the predicate adjective must also be:

feminine, singular, nominative → důležitá

Compare:

Večerní procházka je důležitá. – The evening walk is important. (feminine)
Večerní program je důležitý. – The evening program is important. (masculine)
Večerní jídlo je důležité. – The evening meal is important. (neuter)

The verb je (is) links procházka to důležitá, and they must match.

Can I change the word order, for example to Pro moji rodinu je večerní procházka v parku důležitá?

Yes. Czech has relatively flexible word order, and all of these are grammatically correct:

Večerní procházka v parku je pro moji rodinu důležitá.
Pro moji rodinu je večerní procházka v parku důležitá.
Důležitá je pro moji rodinu večerní procházka v parku.

The differences are mostly about emphasis and information structure:

Starting with Večerní procházka v parku presents the walk itself as the topic.
Starting with Pro moji rodinu emphasizes the family’s point of view.
Putting důležitá near the end often highlights importance as the key piece of information.

Your alternative sentence is natural and idiomatic.

Why is there no word for “a / an / the” before večerní procházka?

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

The noun procházka on its own can mean:

a walk
the walk
walking (in some contexts)

Which English article you use in translation depends on context, not on a specific Czech word. Here, typical translations are:

An evening walk in the park is important for my family.
The evening walk in the park is important for my family.

Czech speakers rely on context, word order, and sometimes demonstratives (e.g. ta procházka) if they need to be very specific.

What is the difference between v parku and something like na parku?

Both v and na can sometimes translate as in / on / at, but they are not interchangeable.

v parku – literally in the park, inside the park area. This is the normal and idiomatic choice.
na parku – would usually sound wrong or very strange in standard Czech.

As a rough guide:

v (+ locative) – inside something: v domě (in the house), v autě (in the car), v parku (in the park).
na (+ locative) – on a surface or at certain places: na stole (on the table), na nádraží (at the station), na hřišti (on the playground), na koncertě (at the concert).

So with park, you normally use v parku.

Could I leave out je and say Večerní procházka v parku pro moji rodinu důležitá?

No. In standard Czech you cannot omit je here.

You need the verb být (to be) in the present tense to form this type of sentence:

X je Y. – X is Y.
Večerní procházka v parku je pro moji rodinu důležitá.

Leaving out je would sound ungrammatical in standard modern Czech in this context.