Ona nikad ne ide bez novčanika i ključa.

Yes, and that is normal and required in Serbian.

Serbian uses negative concord, which means that words like nikad (never) go together with a negated verb:

• nikad ne ide = she never goes

So unlike standard English, where never goes has only one negative word, Serbian usually keeps both:

• nikad ne
• niko ne
• ništa ne

Saying Ona nikad ide would be ungrammatical.

Yes, it could.

Serbian often omits subject pronouns because the verb form already shows the person/number well enough in context. So:

• Ide = he/she goes
• Ona ide = she goes

Including ona can do a few things:

• make the subject explicit
• add contrast or emphasis
• help if the context is not clear

So both are possible:

• Nikad ne ide bez novčanika i ključa.
• Ona nikad ne ide bez novčanika i ključa.

The version with ona is just a bit more explicit.

Ide is the 3rd person singular present tense of ići (to go).

So:

• ja idem = I go
• ti ideš = you go
• on/ona ide = he/she goes

In this sentence, the present tense does not mean she is going right now. With nikad, it expresses a habit or general rule:

• Ona nikad ne ide... = she never goes...

So it means something like she never goes out / never leaves / never goes anywhere without..., depending on context.

Because the preposition bez (without) requires the genitive case.

So the nouns change form:

• novčanik → novčanika
• ključ → ključa

That is why you get:

• bez novčanika i ključa

This literally means without wallet and key, but in natural English you would usually say without a/the wallet and key or without her wallet and key, depending on context.

Here it is singular genitive.

The forms are:

• ključ = key
• ključa = of a key / without a key

So in this sentence, it refers to one key.

If you wanted keys in the plural, the genitive plural would normally be:

• ključeva

So:

• bez ključa = without a key
• bez ključeva = without keys

Good question: novčanika can look ambiguous, because it can be:

• genitive singular of novčanik
• genitive plural of novčanik

But in this sentence, it is understood as singular: without a wallet.

Context usually makes the meaning clear. Since ključa is singular and the sentence is about the things she normally carries, learners will usually understand this as wallet + key, both singular.

Because after the preposition bez, simple i (and) is the normal way to join the nouns.

So:

• bez novčanika i ključa = without a wallet and a key

The idea is that bez applies to both nouns.

Ni is more common in structures like:

• Nema novčanika ni ključa. = There is neither a wallet nor a key.

So in this sentence, i is the natural choice.

In normal usage, it means that she does not go unless she has those things with her.

So the natural understanding is:

• she does not go without her wallet
• she does not go without her key

In English, without a wallet and key can sometimes sound a little ambiguous, but in Serbian this phrasing is very normal.

If someone wanted to be extra explicit, they could repeat bez:

• bez novčanika i bez ključa

But the original sentence is perfectly standard.

Because Serbian often leaves possession unstated when it is obvious from context, especially with personal items.

So bez novčanika i ključa naturally suggests:

• without her wallet
• without her key

If you want to make the ownership more explicit, you can add a possessive, for example:

• bez svog novčanika i svog ključa

But in everyday Serbian, that is often unnecessary if everyone already knows whose items are meant.

Yes.

• nikad and nikada both mean never

The difference is mostly style and rhythm:

• nikad = shorter, very common in speech
• nikada = slightly fuller, sometimes a bit more formal or emphatic

So both are correct:

• Ona nikad ne ide bez novčanika i ključa.
• Ona nikada ne ide bez novčanika i ključa.

Yes, Serbian word order is fairly flexible.

For example, these are all possible:

• Ona nikad ne ide bez novčanika i ključa.
• Nikad ne ide bez novčanika i ključa.
• Bez novčanika i ključa ona nikad ne ide.

But they do not all sound equally neutral. The most natural everyday versions are usually:

• Ona nikad ne ide bez novčanika i ključa.
• Nikad ne ide bez novčanika i ključa.

So the original sentence has a very normal, clear word order.