Sve što nam za večeras još treba jesu mir, topla juha i cesta bez zastoja.

Sve što is a very common Croatian pattern meaning everything that or all that.

So:

• sve = everything / all
• što = that / what, introducing a relative clause

In this sentence, Sve što nam za večeras još treba means Everything that we still need for tonight.

After sve, Croatian very often uses što:

• Sve što znam = Everything that I know
• Sve što trebamo = Everything that we need

Because treba belongs to the relative clause što nam za večeras još treba, and inside that clause it relates to sve, which is grammatically singular.

So Croatian is basically saying:

• sve ... treba = everything ... is needed

Even though the sentence later names three items, the grammar inside the relative clause is still built around sve.

A useful comparison:

• Treba nam mir. = We need peace.
• Trebaju nam knjige. = We need books.
• Sve što nam treba... = Everything that we need...

In your sentence, sve is the key reason for singular treba.

Because jesu connects the opening phrase with a list of multiple things:

• mir
• topla juha
• cesta bez zastoja

That list is plural as a whole, so plural jesu is natural.

So the sentence works like:

• Everything we still need for tonight is/are the following things: peace, warm soup, and a road without delays.

In Croatian, with this kind of sentence, plural agreement like jesu is very common when the complement is a plural list.

You may also hear singular je in similar sentences in everyday speech, especially with sve što..., but jesu clearly matches the multiple items being named.

Both are forms of biti = to be.

• su = unstressed clitic form
• jesu = full, stressed form

In a sentence like this, jesu sounds a bit more formal, careful, or emphatic. It can also give the sentence a slightly literary tone.

So:

• Sve što nam za večeras još treba su mir, topla juha i cesta bez zastoja.
• Sve što nam za večeras još treba jesu mir, topla juha i cesta bez zastoja.

Both are understandable, but jesu feels a bit fuller and more deliberate here.

Nam is the dative form of mi = we/us.

Here it means to us, and with trebati Croatian often uses the dative for the person who needs something:

• Treba nam odmor. = We need rest.
• Literally: Rest is needed to us.

So:

• nam = to us / for us

That is why the sentence does not use something like an English-style direct object for us.

Because nam is a clitic, and Croatian clitics tend to go near the beginning of their clause, usually in the second position area.

Here the relative clause begins with što, and then the clitic appears immediately after it:

• što nam za večeras još treba

That order sounds very natural in Croatian.

English speakers often expect something more like što još treba nam, but that would not sound right in standard Croatian.

Večeras means tonight / this evening.

Za večeras means for tonight or as far as tonight is concerned.

So there is a small difference:

• Večeras trebamo mir. = Tonight we need peace.
• Za večeras nam treba mir. = For tonight, we need peace.

In your sentence, za večeras frames the need as something specific to tonight’s situation.

Here još means still or yet.

So:

• još treba = still needs / is still needed

The idea is: Everything that we still need for tonight...

In other contexts, još can also mean more:

• još juhe = more soup

But in this sentence it means still/yet, not more.

Because they are not direct objects here.

With trebati, the thing needed is often in the nominative:

• Treba nam mir.
• Treba nam topla juha.

And after jesu, the listed nouns are also in the nominative as part of the sentence’s main predicative structure.

So you get:

• mir — nominative singular
• topla juha — nominative singular
• cesta — nominative singular

Even though English uses object-like wording (we need X), Croatian often structures this more like X is needed to us.

Because the preposition bez always takes the genitive.

So:

• bez = without
• zastoj = delay / traffic jam / stoppage
• bez zastoja = without delay / without traffic jams

The form zastoja is genitive. In fact, for this noun, the genitive singular and genitive plural look the same, so context tells you the exact nuance.

In this sentence, English naturally understands it as something like a road without traffic jams/delays.

Yes. Croatian word order is fairly flexible.

For example, you could also say:

• Mir, topla juha i cesta bez zastoja jesu sve što nam za večeras još treba.

That version puts the list first.

The original sentence starts with Sve što nam za večeras još treba..., which creates a smoother, more reflective buildup and saves the actual list for the end. That makes it sound a bit more elegant or literary.

So the given order is not random: it is a stylistic choice.

Because neither comma is needed here.

• No comma before što: this is a restrictive relative clause, closely tied to sve. It defines what sve means, so Croatian normally does not set it off with commas.
• No comma before jesu: you do not put a comma between the subject part and the main verb just because the subject is long.

So the sentence is correctly punctuated as written.