Woda szkodzi aksamitowi.

Because the verb szkodzić requires the dative case for the thing or person being harmed.

So the pattern is:

• kto/co szkodzi komu/czemu
• someone/something harms someone/something

Here:

• woda = the subject, so it stays in the nominative
• aksamitowi = the thing being harmed, so it goes into the dative

Base form:

• aksamit = velvet

Dative form:

• aksamitowi = to velvet / for velvet, but in English we usually just say harms velvet

Woda is in the nominative case, because it is the subject of the sentence — the thing doing the action.

In this sentence:

• Woda = water
• szkodzi = harms / is harmful
• aksamitowi = to velvet

So literally, the structure is something like:

• Water harms to velvet

But natural English is simply:

• Water harms velvet
• or Water is bad for velvet

Yes, normally szkodzić takes the dative.

You learn it as:

• szkodzić komuś / czemuś = to harm someone / something

Examples:

• Dym szkodzi zdrowiu. = Smoke harms health.
• Słońce szkodzi skórze. = The sun harms the skin.
• To szkodzi dzieciom. = This harms children.

So aksamitowi is exactly what we expect after szkodzić.

Because aksamit would be the wrong case here.

A native English speaker might expect the direct object pattern:

• subject + verb + object

But Polish does not always work that way. Some verbs require a specific case, and szkodzić is one of them. It does not take the accusative here; it takes the dative.

So:

• ❌ Woda szkodzi aksamit
• ✅ Woda szkodzi aksamitowi

The dictionary form is szkodzić.

Szkodzi is the 3rd person singular present tense form, used with:

• on = he
• ona = she
• ono = it

and also with singular nouns like woda.

So:

• woda szkodzi = water harms
• on szkodzi = he harms
• to szkodzi = this harms

Szkodzić is imperfective.

That means it is used for:

• general truths
• repeated actions
• ongoing situations
• habitual meaning

That fits this sentence well, because Woda szkodzi aksamitowi sounds like a general fact: water is harmful to velvet.

The common perfective partner is zaszkodzić.

Compare:

• Woda szkodzi aksamitowi. = Water is harmful to velvet. / Water harms velvet.
• Woda zaszkodziła aksamitowi. = Water harmed the velvet. / The water caused damage to the velvet.

Because Polish has no articles.

English uses:

• a
• an
• the

Polish does not.

So woda can mean:

• water
• the water

And aksamitowi can refer to:

• velvet
• the velvet

You understand the exact meaning from context.

Yes. Polish word order is more flexible than English because the case endings show grammatical roles.

So all of these can work, depending on emphasis:

• Woda szkodzi aksamitowi.
• Aksamitowi szkodzi woda.
• Szkodzi aksamitowi woda.

The most neutral version here is probably:

• Woda szkodzi aksamitowi.

If you move aksamitowi to the front, you emphasize velvet more:

• Aksamitowi szkodzi woda. = As for velvet, water is harmful to it.

A rough English-friendly guide:

• Woda ≈ VO-da
• szkodzi ≈ SHKO-djee
• aksamitowi ≈ ak-sa-mee-TO-vee

A few pronunciation points:

• w in Polish sounds like English v
• sz sounds like English sh
• dzi here sounds roughly like jee in jeep, but softer
• stress in Polish usually falls on the second-to-last syllable

So the stress is:

• WO-da
• SZKO-dzi
• ak-sa-mi-TO-wi

Because aksamit is a masculine noun, and one common dative singular ending for masculine nouns is -owi.

So:

• nominative: aksamit
• dative: aksamitowi

This is a very common pattern:

• student → studentowi
• kot → kotowi
• ojciec → ojcu (irregular pattern)
• aksamit → aksamitowi

Not every masculine noun uses exactly the same ending in every case, but -owi is very common in the dative singular.

Here it is being used as a material noun, like velvet in English.

So the sentence is not about a velvet as one object. It is about the fabric/material in general.

That is why the sentence sounds like a general statement:

• Water is bad for velvet
• Water harms velvet

Polish often uses the singular form for this kind of general statement.

Yes. In natural English, Water is bad for velvet is often the most idiomatic translation.

The Polish verb szkodzić means to harm, to be harmful to, or to be bad for, depending on context.

So this sentence could be understood naturally as:

• Water harms velvet
• Water is harmful to velvet
• Water is bad for velvet

All of these match the Polish structure well.

You add nie before the verb:

• Woda nie szkodzi aksamitowi.

This means:

• Water does not harm velvet
• Water isn’t harmful to velvet

The case after szkodzić stays the same, so it is still aksamitowi in the dative.

You would ask the dative question:

• Komu? Czemu? = To whom? To what?

So:

• Czemu szkodzi woda? = What does water harm? / What is water harmful to?
• Aksamitowi. = Velvet.

This is a standard Polish way to identify the case a verb requires. For szkodzić, the question is:

• komu? czemu?
  which tells you it takes the dative.