Šetam psa u parku.

Because psa is the accusative singular form of pas (dog).

In Šetam psa, the dog is the direct object of the verb šetati in the sense of to walk someone/something. Serbian marks that object with case.

For masculine animate nouns, the accusative singular usually matches the genitive singular, so:

• pas = nominative singular
• psa = accusative singular

So:

• Pas šeta. = The dog is walking.
• Šetam psa. = I am walking the dog.

Šetam is the 1st person singular present tense form of šetati.

It means:

• I walk
• I am walking

Which English translation fits best depends on context. Serbian present tense often covers both the simple present and the present continuous.

A few present-tense forms of šetati are:

• šetam = I walk / am walking
• šetaš = you walk / are walking
• šeta = he/she/it walks / is walking
• šetamo = we walk / are walking
• šetate = you (plural/formal) walk / are walking
• šetaju = they walk / are walking

Because Serbian usually does not need subject pronouns unless you want emphasis or contrast.

The ending -am in šetam already tells you the subject is I.

So:

• Šetam psa u parku. = normal, natural
• Ja šetam psa u parku. = I am walking the dog in the park (emphatic, maybe contrasting with someone else)

English usually needs I, but Serbian often leaves it out.

Because u can take different cases depending on meaning.

Here it means in the park as a location, so Serbian uses the locative:

• park = nominative
• parku = locative singular

So:

• u parku = in the park

Compare:

• Ja sam u parku. = I am in the park.
• Idem u park. = I am going to the park.

That second sentence uses u + accusative because it expresses movement toward a destination.
Your sentence uses u + locative because it tells you where the walking happens.

It means I am taking the dog for a walk / walking the dog.

The verb is being used transitively here: the dog is the object of the action.

If you want to say that you yourself are walking, Serbian often uses the reflexive form:

• Šetam se. = I am taking a walk / walking around.

So there is an important difference:

• Šetam psa. = I am walking the dog.
• Šetam se sa psom. = I am walking with the dog / I am taking a walk with the dog.

That distinction is very useful for learners.

Šetati is imperfective.

That means it is used for:

• ongoing actions
• repeated actions
• habitual actions
• general descriptions

So Šetam psa u parku can mean either:

• I’m walking the dog in the park (right now), or
• I walk the dog in the park (habitually),

depending on context.

A common related perfective verb is prošetati:

• Prošetaću psa. = I will take the dog for a walk.
• Prošetao sam psa. = I took the dog for a walk.

Very roughly:

• šetati = the activity/process
• prošetati = one completed walk / taking someone for a walk

Yes. Serbian word order is fairly flexible because case endings show grammatical roles.

The neutral order here is:

• Šetam psa u parku.

But you could also hear:

• Psa šetam u parku.
• U parku šetam psa.

These versions are not random; they shift emphasis or topic.

For example:

• Šetam psa u parku. = neutral statement
• Psa šetam u parku. = emphasizes the dog
• U parku šetam psa. = emphasizes in the park

English relies much more on fixed word order, so this often feels unusual to learners.

Because Serbian does not have articles like English a/an and the.

So pas, psa, park, parku, etc. do not automatically show whether something is a dog, the dog, a park, or the park. Context tells you that.

So Šetam psa u parku can naturally be translated as:

• I’m walking the dog in the park

If the context were different, English might choose:

• I’m walking a dog in a park

Serbian leaves that distinction unstated unless something else makes it clear.

A simple English-friendly guide would be:

• Š sounds like sh in shoe
• č would sound like ch, but there is no č here
• r in Serbian is rolled or tapped
• vowels are usually clear and consistent:
  • a like a in father
  • e like e in met
  • u like oo in food

Approximate pronunciation:

• Šetam ≈ SHEH-tam
• psa ≈ psah
• u ≈ oo
• parku ≈ PAR-koo

Put together:

• SHEH-tam psah oo PAR-koo

The p in psa is pronounced; Serbian allows clusters like ps- at the beginning of a syllable.

Not with the same meaning.

Voditi means to lead / take / guide.
So Vodim psa usually means I am leading/taking the dog somewhere, not specifically walking the dog for exercise.

Compare:

• Šetam psa. = I am walking the dog.
• Vodim psa kod veterinara. = I am taking the dog to the vet.

So in your sentence, šetam is the natural choice if the idea is taking the dog for a walk.

Yes.

Serbian present tense often covers both meanings, and context decides which one is intended.

So Šetam psa u parku can describe:

1. a current action

   • right now, I am walking the dog in the park

2. a habitual action

   • I regularly walk the dog in the park

If you want to make the meaning clearer, Serbian can add time words:

• Sada šetam psa u parku. = I am walking the dog in the park now.
• Svaki dan šetam psa u parku. = I walk the dog in the park every day.