Kad vodim psa van, uvijek nosim povodac, a on veselo maše repom.

Both kad and kada mean when.

• kad is the shorter, very common everyday form
• kada is a bit fuller and can sound slightly more formal or emphatic

In this sentence, Kad vodim psa van... is completely natural conversational Croatian.

Because pas is the direct object of vodim (I take / I lead), it goes into the accusative case.

• nominative: pas = dog (subject form)
• accusative: psa = dog (object form)

So:

• Pas ide van. = The dog goes outside.
• Vodim psa van. = I’m taking the dog outside.

This is a very common pattern with masculine animate nouns in Croatian: the accusative often looks like the genitive.

Literally, voditi often means to lead or to take. In the context of a dog, vodim psa van means something like:

• I take the dog outside
• I’m walking the dog outside
• I’m taking the dog out

So yes, the core idea is lead/take, but in natural English this would usually be translated more idiomatically.

Van means out / outside, especially with movement toward the outside.

So:

• vodim psa van = I take the dog outside

By contrast, vani usually means outside in a location sense:

• Pas je vani. = The dog is outside.

A useful contrast:

• Idem van. = I’m going out.
• Ja sam vani. = I’m outside.

Because Croatian verb endings usually already show the subject.

• vodim = I lead / I take
• nosim = I carry / I wear

So the pronoun ja is usually omitted unless you want emphasis or contrast.

For example:

• Vodim psa van. = I take the dog outside.
• Ja vodim psa van, ne ti. = I’m the one taking the dog outside, not you.

This is very normal in Croatian.

Uvijek means always.

In this sentence:

• uvijek nosim povodac = I always carry a leash

Its position is flexible, but this placement is very natural. Croatian word order is more flexible than English, though not random. You could also hear:

• Kad vodim psa van, nosim uvijek povodac.

But uvijek nosim povodac sounds more standard and natural here.

Povodac is in the accusative singular, because it is the direct object of nosim (I carry).

Here, the form happens to be the same as the nominative:

• nominative: povodac
• accusative: povodac

That is normal for many inanimate masculine nouns in Croatian.

Compare:

• Imam povodac. = I have a leash.
• Nosim povodac. = I carry a leash.

Here a is a conjunction that often means something like:

• and
• while
• whereas
• and meanwhile

In this sentence:

• ..., a on veselo maše repom.
• ..., and he happily wags his tail.

It does not work exactly like English and in every context. Croatian a often links two parallel or contrasting ideas in a very natural way.

Compare roughly:

• i = simple and
• a = and / while / whereas depending on context

Here a is a very good choice because it smoothly shifts attention from what I do to what the dog does.

Yes. On means he, and it can refer to a male animal, especially a specific dog.

Since pas is grammatically masculine, using on is perfectly natural. It can also reflect that the dog is being treated as an individual, not just as an object.

So:

• on = he
• referring to the dog

If the dog were female, you might have:

• ..., a ona veselo maše repom.

Because the verb mahati / mašati normally takes the instrumental case for the thing being waved.

So:

• rep = nominative
• repom = instrumental

That is why we say:

• maše repom = wags his tail
• literally, waves with his tail

Other similar examples:

• Maše rukom. = He/She waves a hand.
• Mašem zastavom. = I’m waving a flag.

This is a very important verb pattern to remember: mahati + instrumental.

Veselo means happily / cheerfully here.

It is an adverb, describing how the dog is wagging its tail:

• veselo maše repom = he happily wags his tail

It comes from the adjective veseo / vesela / veselo (cheerful, happy), but in this sentence it functions adverbially.

A few similar examples:

• brzo trči = runs quickly
• glasno laje = barks loudly
• veselo maše repom = wags his tail happily

Because in Croatian, the present tense is commonly used for repeated, habitual actions, just like in English:

• Kad vodim psa van, uvijek nosim povodac...
• When I take the dog outside, I always carry a leash...

This does not mean only right now. It can also mean:

• what usually happens
• what someone regularly does
• a general habit

The word uvijek strongly reinforces that habitual meaning.

In Croatian, it can cover both kinds of English phrasing depending on context.

So this clause can be understood as:

• When I take the dog outside
• Whenever I take the dog outside
• sometimes even When I’m taking the dog outside

Because the whole sentence includes uvijek (always), the meaning is clearly habitual:

• Whenever I take the dog outside, I always carry a leash...

So the natural English sense is more general/habitual than one specific occasion.

Yes, Croatian word order is fairly flexible, but different orders can sound more or less natural depending on emphasis.

The given sentence is very natural:

• Kad vodim psa van, uvijek nosim povodac, a on veselo maše repom.

Some variations are possible, for example:

• Kad psa vodim van, uvijek nosim povodac, a on veselo maše repom.
• Kad vodim psa van, povodac uvijek nosim, a on veselo maše repom.

These are grammatically possible, but they may sound more marked or put focus on different words. For learners, the original word order is a good model to follow.