Learn Hardcore Croatian: Turisti kažu da je naš mali festival ne samo zabavan, nego i važan za život u susjedstvu. - Tourists say that our little festival is not only fun, but also important for life in the neighborhood.

da je naš mali festival ne samo zabavan, nego i važan za život u susjedstvu
= that our small festival is not only fun, but also important for life in the neighbourhood.

Je is the 3rd person singular of biti (to be). In Croatian, in clauses introduced by da, the verb usually comes early in the clause, so:

da je naš mali festival... (that is our small festival...)

is more natural than da naš mali festival je.... The second version is not wrong, but it sounds marked or emphatic. Standard neutral word order here is da je + subject + rest.

Why is there no comma before da in Turisti kažu da je...?

In modern standard Croatian, when da introduces an object clause (what someone says, thinks, believes, etc.), there is usually no comma:

Turisti kažu da je... (Tourists say that…)
Mislim da je to dobra ideja. (I think that this is a good idea.)
Vjerujem da će doći. (I believe that he/she will come.)

Older or more formal styles sometimes put a comma, but the current norm is without a comma after verbs like reći, kazati, misliti, vjerovati when followed by da.

Why are the adjectives naš and mali before festival, and how do they agree with it?

In Croatian, attributive adjectives (adjectives that directly describe a noun) normally come before the noun:

naš mali festival = our small festival

They must agree with the noun in:

Gender: festival is masculine
Number: here it is singular
Case: in this sentence, festival is the subject in the subordinate clause, so nominative singular

So you get:

naš (masculine singular nominative)
mali (masculine singular nominative)
festival (masculine singular nominative)

Together: naš mali festival.

How does the structure ne samo ... nego i ... work? Is it the same as not only ... but also ... in English?

Yes, ne samo ... nego i ... corresponds directly to English not only ... but also ....

In this sentence:

ne samo zabavan = not only fun
nego i važan = but also important

So the pattern is:

ne samo
- first element
nego i
- second element

Examples with the same structure:

On je ne samo pametan, nego i marljiv.
= He is not only smart, but also hard-working.
Knjiga je ne samo zanimljiva, nego i korisna.
= The book is not only interesting, but also useful.

Note that i in nego i adds the meaning also/as well.

Why is je only said once (before ne samo zabavan) and not repeated before važan?

The verb je is shared by both adjectives:

je ne samo zabavan, nego i važan
= is not only fun, but also important

Croatian (like English) often avoids repeating the same verb in parallel structures. Grammatically, it would also be correct to repeat it:

da je naš mali festival ne samo zabavan, nego je i važan za život u susjedstvu.

This just sounds slightly heavier; most speakers prefer the shorter version with je only once.

Why are zabavan and važan masculine singular, and not plural to match turisti?

Because they describe festival, not turisti.

The main clause:

Turisti kažu = Tourists say

The subordinate clause:

da je naš mali festival ne samo zabavan, nego i važan...
= that our small festival is not only fun, but also important...

Inside the da-clause, the subject is naš mali festival (masculine singular), so the predicate adjectives must agree with festival:

zabavan (masculine singular)
važan (masculine singular)

They do not agree with turisti, because the tourists are not the thing being fun/important; they are the ones saying it.

Why is it važan za život, not something like važan životu?

Croatian often uses the pattern:

važan za + accusative = important for

So:

važan za život = important for life
važan za grad = important for the city
važan za obitelj = important for the family

Using a bare dative (važan životu) is not idiomatic here. Some other adjectives can take dative objects without a preposition, but važan very commonly uses za + accusative to express for/to in this sense.

Which case is život in, and why?

Život here is in the accusative singular.

Reason:

The preposition za (for) requires the accusative case.
The noun život has the same form for nominative and accusative singular, so it looks the same, but functionally it is accusative after za.

So: za život = for life (life = accusative object of za).

What case is susjedstvu, and what is the difference between u susjedstvu and u susjedstvo?

Susjedstvu is in the locative singular.

u
- locative = location (where something is)
u
- accusative = direction (where something is going)

So:

u susjedstvu (locative) = in the neighbourhood (location, static)
- važan za život u susjedstvu = important for life in the neighbourhood
u susjedstvo (accusative) = into the neighbourhood (movement, direction)
- Selimo se u susjedstvo. = We are moving into the neighbourhood.

In the given sentence, we talk about life in the neighbourhood (a place, not movement), so locative u susjedstvu is used.

What is the tense/aspect of kažu, and could we also use rekli su or govore here?

Kažu is the present tense, 3rd person plural of kazati (to say). It means they say (now or generally).

Possible alternatives:

Turisti kažu da je...
= Tourists say that... (general, timeless or present)
Turisti su rekli da je...
= Tourists said that... (past, completed; more like a report of a specific event)
Turisti govore da je...
= Tourists are saying / keep saying that... (focus on the ongoing activity of speaking, or a repeated statement)

In the original sentence, kažu suggests what tourists generally say about the festival (or what they are currently saying), without emphasising a single past occasion.