Kada idem u grad, uvek nosim novčanik sa sobom.

Because this sentence describes a habit or general routine: Whenever I go into town, I always carry my wallet with me.

In Serbian, the present tense is often used for repeated or habitual actions, just like in English:

• Kada idem u grad... = When/Whenever I go to town...

It does not mean only right now I am going. In this context, it means whenever I go.

Kada and kad both mean when.

• kada is the fuller form
• kad is a shorter, very common form in everyday speech

So both are possible here:

• Kada idem u grad, uvek nosim novčanik sa sobom.
• Kad idem u grad, uvek nosim novčanik sa sobom.

The meaning is the same. Kada can sound a little more neutral or slightly more formal.

This is about case.

After u, Serbian can use different cases depending on the meaning:

• u + accusative = movement into somewhere
• u + locative = being in somewhere

So:

• idem u grad = I am going to town / into town
  → movement, so grad is in the accusative
• ja sam u gradu = I am in town
  → location, so gradu is in the locative

That is why the sentence uses u grad.

Grad literally means city or town.

But in phrases like ići u grad, it often has a broader everyday meaning, something like:

• go into town
• go downtown
• go to the city center / out into town

So it does not always mean going to a specific large city. It can simply mean going out to the urban center or main part of town.

Uvek means always.

It usually goes before the verb it modifies, so:

• uvek nosim = I always carry

That placement is very natural. Serbian word order is fairly flexible, but some positions sound more neutral than others.

Natural versions include:

• Kada idem u grad, uvek nosim novčanik sa sobom.
• Uvek nosim novčanik sa sobom kada idem u grad.

Both are correct, but the original sentence is a very normal way to say it.

Yes, nositi can mean both to carry and to wear, depending on context.

Here, with novčanik (wallet), it clearly means:

• to carry
• to have on one’s person

So:

• nosim novčanik = I carry a wallet / I have my wallet with me

With clothes, nositi means to wear:

• Nosim kaput. = I’m wearing a coat.

Because novčanik is the direct object of nosim, and here it is a masculine noun in the accusative singular.

For many inanimate masculine nouns, the accusative singular looks exactly like the nominative singular.

So:

• nominative: novčanik
• accusative: novčanik

That is why the form does not change.

Compare that with an animate masculine noun, where accusative often changes:

• vidim čoveka = I see the man

But:

• nosim novčanik = I carry the wallet

Sa sobom means with oneself / with me / with you / with him/her, depending on the subject.

In this sentence:

• nosim novčanik sa sobom = I carry my wallet with me

The word sobom comes from the reflexive pronoun sebe and refers back to the subject.

Examples:

• Nosim ključ sa sobom. = I carry the key with me.
• Ona nosi pasoš sa sobom. = She carries her passport with her.

So sa sobom is a very common way to say with me/you/himself/herself, when it refers back to the subject of the sentence.

Serbian often uses the reflexive pronoun when the with phrase refers back to the subject.

So instead of saying something equivalent to with me, Serbian commonly says:

• sa sobom = with myself / with oneself, but in natural English this becomes with me

Since the subject is I in idem / nosim, sobom refers back to I.

You can think of it like this:

• Nosim novčanik sa sobom.
  literally: I carry the wallet with myself.
  natural English: I carry the wallet with me.

This is standard Serbian usage.

Yes, in many contexts you can hear uz sebe, and it often means something like:

• on oneself
• close at hand
• with one

For example:

• Imam novčanik uz sebe. = I have my wallet on me.

But in your sentence, nosim novčanik sa sobom is the most natural neutral choice.

Very roughly:

• sa sobom focuses on having it with you
• uz sebe can suggest on your person / close to you

Both are possible in some situations, but sa sobom is especially common here.

No. Serbian usually does not need the subject pronoun if it is already clear from the verb ending.

Here:

• idem = I go / I am going
• nosim = I carry

So ja is understood automatically.

You could say:

• Kada ja idem u grad, uvek nosim novčanik sa sobom.

But adding ja gives extra emphasis, something like:

• When I go into town, I always carry my wallet with me.

Without emphasis, leaving it out is more natural.

The word order can change, because Serbian is more flexible than English. But some versions sound more natural or emphasize different parts.

The original sentence is very natural:

• Kada idem u grad, uvek nosim novčanik sa sobom.

Other possible orders:

• Uvek nosim novčanik sa sobom kada idem u grad.
• Novčanik uvek nosim sa sobom kada idem u grad.

These all mean roughly the same thing, but the emphasis shifts:

• uvek early in the sentence highlights always
• novčanik early gives more emphasis to wallet

So the word order is flexible, but not random.

Yes. In this kind of sentence, kada often means whenever.

• Kada idem u grad, uvek nosim novčanik sa sobom.

This is not talking about one specific trip. It means a repeated situation:

• Whenever I go into town, I always carry my wallet with me.

So depending on context, English might translate kada as either:

• when
• whenever

Here, whenever captures the sense very well.