Sierść naszego psa jest mokra po spacerze, więc wycieram ją ręcznikiem.

Sierść means an animal’s hair/coat/fur, especially the actual body hair of a dog, cat, and similar animals.

• włosy = hair on a person’s head, or hair in general
• futro = fur, but often more like a thick furry coat, or even a fur garment
• sierść = the natural coat/hair of an animal

So for a dog, sierść is a very natural choice.

Because psa is in the genitive case.

In sierść naszego psa, the idea is the coat of our dog. In Polish, possession is very often expressed by putting the possessor into the genitive:

• pies = dog
• psa = of the dog

And the adjective has to match that case too:

• nasz = our
• naszego = of our

So:

• sierść naszego psa = our dog’s coat / the coat of our dog

Because mokra has to agree with sierść, which is a feminine singular noun.

In Polish, adjectives match the noun in gender, number, and case.

• sierść is feminine
• therefore the adjective must also be feminine:
  • mokra = wet (feminine singular)

Compare:

• pies jest mokry = the dog is wet
• sierść jest mokra = the coat/fur is wet
• futro jest mokre = the fur/coat is wet (if the noun is neuter)

Because the preposition po here means after, and in this meaning it requires the locative case.

• spacer = walk
• spacerze = after/on the walk (locative form after po)

So:

• po spacerze = after the walk

This is a very common pattern:

• po pracy = after work
• po obiedzie = after lunch
• po lekcji = after class

więc means so, therefore, or thus. It shows a result.

In this sentence:

• the dog’s coat is wet after the walk,
• so I dry/wipe it with a towel.

Compare:

• i = and
• ale = but
• więc = so / therefore

So więc is the best connector here because the second action happens as a consequence of the first situation.

wycieram is the 1st person singular present tense of wycierać.

It means something like:

• I wipe
• I dry by wiping
• I towel off

In context, wycieram ją ręcznikiem means you are drying the dog’s coat by using a towel.

Polish often uses one verb where English might choose among several depending on context.

ją refers back to sierść.

Since sierść is feminine singular, the object pronoun must also be feminine singular:

• ją = her/it (accusative feminine singular)

Here it means it, because it refers to the coat/fur.

So:

• wycieram ją = I wipe/dry it

You could also repeat the noun:

• wycieram sierść ręcznikiem

But using ją sounds more natural because the noun was just mentioned.

Because the verb wycierać takes a direct object in the accusative case, and the accusative feminine singular pronoun is ją.

Compare:

• ją = her/it (accusative, direct object)
• jej = her (usually dative or genitive)
• nią = her/it (instrumental)

So in:

• wycieram ją = I wipe/dry it

the pronoun has to be ją.

Because ręcznikiem is in the instrumental case, which is often used to show the tool or means used to do something.

• ręcznik = towel
• ręcznikiem = with a towel

So:

• wycieram ją ręcznikiem = I wipe/dry it with a towel

This is a very common use of the instrumental:

• piszę długopisem = I write with a pen
• kroję nożem = I cut with a knife

Yes. Polish usually does not need the subject pronoun if the verb ending already makes the subject clear.

• wycieram already means I am wiping / I wipe

So Polish normally says:

• wycieram ją ręcznikiem

not:

• ja wycieram ją ręcznikiem

You can add ja for emphasis, contrast, or clarity, but it is not necessary.

Not completely. Polish word order is more flexible than English, although some versions sound more natural than others.

The given sentence is very natural:

• Sierść naszego psa jest mokra po spacerze, więc wycieram ją ręcznikiem.

But other orders are possible for emphasis, for example:

• Po spacerze sierść naszego psa jest mokra, więc wycieram ją ręcznikiem.
• Sierść naszego psa po spacerze jest mokra, więc wycieram ją ręcznikiem.

The basic meaning stays the same, but the focus shifts slightly. English learners often expect one rigid order, but Polish uses word order more for emphasis and information structure.

Yes, possibly, but the nuance is a little different.

• wycierać = to wipe, to towel off
• suszyć = to dry

If you use a towel and the physical wiping action is important, wycieram ją ręcznikiem is very natural.

If you want to focus more generally on making it dry, suszę ją ręcznikiem can also work, though it may sound slightly less specific in this context.

So:

• wycieram ją ręcznikiem = I’m drying it by wiping it with a towel
• suszę ją ręcznikiem = I’m drying it with a towel

Because the main subject of the sentence is still sierść, and sierść is in the nominative.

The phrase naszego psa is only a dependent phrase showing possession:

• sierść = subject, nominative
• naszego psa = possessor, genitive

Since mokra describes sierść, it agrees with sierść, not with psa.

So:

• sierść → nominative feminine singular
• mokra → nominative feminine singular

Yes, it sounds natural and correct.

It is a good, standard Polish sentence. A native speaker might also say slightly different versions depending on style, for example:

• Po spacerze sierść naszego psa jest mokra, więc wycieram ją ręcznikiem.
• Sierść naszego psa jest mokra po spacerze, więc osuszam ją ręcznikiem.

But the original sentence is fully natural and idiomatic.