Prodavac nema ni saobraćajnu dozvolu ni servisnu knjižicu.

Nema is the 3rd person singular negative form of imati (to have).

• imati = to have
• ima = he/she/it has
• nema = he/she/it does not have

So:

• Prodavac ima... = The seller has...
• Prodavac nema... = The seller does not have...

In this sentence, prodavac is singular, so nema is the correct form.

Ni ... ni ... means neither ... nor ....

So:

• nema ni saobraćajnu dozvolu ni servisnu knjižicu = doesn’t have either the registration document or the service booklet = has neither the registration document nor the service booklet

A very important Serbian pattern is that ni ... ni ... normally appears with a negative verb:

• nema ni X ni Y

This is called negative concord. In Serbian, multiple negative elements are normal and correct.

They are in the accusative singular, because they are direct objects of the verb nema.

The dictionary forms are:

• saobraćajna dozvola
• servisna knjižica

But in the accusative singular, feminine nouns and their adjectives change:

• saobraćajna dozvola → saobraćajnu dozvolu
• servisna knjižica → servisnu knjižicu

So the sentence uses the object forms, not the basic dictionary forms.

Because in Serbian, adjectives must agree with the noun they describe.

That means they match the noun in:

• gender
• number
• case

Here, dozvola is:

• feminine
• singular
• accusative

So the adjective saobraćajna must also become feminine singular accusative:

• saobraćajna → saobraćajnu

The same thing happens in:

• servisna knjižica → servisnu knjižicu

This kind of agreement is a basic feature of Serbian grammar.

Yes, but in modern everyday Serbian, the accusative is very common and natural with concrete direct objects like these.

So this sentence:

• Prodavac nema ni saobraćajnu dozvolu ni servisnu knjižicu.

sounds perfectly normal.

You may learn that older, more formal, or more stylistically marked Serbian sometimes uses the genitive with negation, but for a learner, the safest takeaway is:

• with sentences like this, the accusative is completely standard and common

Prodavac means seller, salesman, or sometimes more generally vendor.

It is a masculine noun. For a specifically female seller, Serbian often uses:

• prodavačica = saleswoman / female seller

In many contexts, prodavac may simply refer to the seller without emphasizing gender, depending on the situation.

Literally, it means something like service booklet.

In real usage, it usually refers to a vehicle’s:

• service record
• maintenance booklet
• service history booklet

So it is not just any little book; it is specifically the document showing the car’s maintenance history.

Because Serbian has no articles.

So Serbian nouns do not have separate words for:

• a / an
• the

That means prodavac can mean:

• a seller
• the seller

and the exact meaning depends on context.

The same is true for:

• saobraćajna dozvola
• servisna knjižica

Context tells you whether English should use a, the, or no article at all.

You could hear structures like that, but ni ... ni ... is the clearest and most idiomatic way to say neither ... nor.

Compare:

• nema ni X ni Y = has neither X nor Y
• nema X i Y = literally “doesn’t have X and Y,” which is understandable, but less neat if your goal is specifically neither ... nor

So in this sentence, ni ... ni ... is the best choice.

The given word order is the most neutral and natural:

• Prodavac nema ni saobraćajnu dozvolu ni servisnu knjižicu.

Serbian word order is more flexible than English, so parts of the sentence can move for emphasis. But for a learner, this version is the safest standard pattern:

• subject + negative verb + ni ... ni ...

So yes, word order can change, but this sentence is the normal one to learn first.

A learner may especially notice these letters:

• ć in saobraćajnu, knjižicu
• ž in knjižicu
• č does not appear here, but learners often compare it with ć

A rough guide:

• ž sounds like the s in measure
• ć is a soft sound, somewhat like a very soft ch/t sound
• č is a harder ch sound, like in church

Also:

• knjižica begins with knj-, which English speakers may find tricky.
  It is roughly k-nyee-zhee-tsa, though that is only an approximation.

As always, it is best to learn these by listening, since English spelling cannot capture them exactly.