Władza zamyka przystań kajakową.

Here władza most naturally means the authorities or the government/administration.

Literally, władza can also mean power or authority in an abstract sense, but in this sentence it refers to the people or institution in control.

So even though English often uses a plural expression like the authorities, Polish can use the singular noun władza.

Because władza is a singular collective noun in Polish.

It works a bit like English the government:

• The government is closing...
• Władza zamyka...

Both are grammatically singular, even though they refer to a group of people.

You may also see władze in Polish, which is a plural form meaning the authorities, but władza gives more of a collective, institutional feel.

Zamyka is:

• 3rd person singular
• present tense
• imperfective
• from the verb zamykać = to close

Because the subject is władza (singular), the verb is also singular: zamyka.

As an imperfective present form, it can describe:

• an action happening now,
• a general action,
• or something presented as ongoing/in progress, depending on context.

Its perfective partner is zamknąć. For example:

• Władza zamyka przystań = the authority is closing / closes the marina
• Władza zamknie przystań = the authority will close the marina

Yes. Przystań is a feminine noun.

This is a common pattern in Polish: some feminine nouns end in a consonant, especially a soft consonant, rather than -a. Other examples are:

• myśl = thought
• noc = night
• twarz = face

So you simply have to learn przystań as feminine.

Because the phrase is the direct object of the verb zamyka, so it has to be in the accusative case.

The dictionary form is:

• przystań kajakowa = nominative

In this sentence, it becomes:

• przystań kajakową = accusative

What changes here?

• przystań stays the same
• kajakowa changes to kajakową

That is completely normal.

Because Polish case endings do not always show up on every word in the same way.

Here:

• przystań is a feminine noun whose nominative singular and accusative singular look the same
• kajakowa is an adjective, and feminine adjectives in the accusative singular change -a to -ą

So:

• nominative: przystań kajakowa
• accusative: przystań kajakową

This is a very useful pattern to remember:

• feminine adjective -a → -ą in the accusative singular

Kajakowa is an adjective built from kajak = kayak.

So przystań kajakowa literally means something like:

• kayak marina
• kayak landing
• kayak harbor
• kayaking dock/facility

The exact English wording depends on context, but grammatically kajakowa simply means related to kayaks.

Yes. Polish word order is more flexible than English because the case endings show who is doing what.

The neutral order here is:

• Władza zamyka przystań kajakową.

But other orders are possible for emphasis, for example:

• Przystań kajakową zamyka władza.
  Emphasis on the kayak marina
• Zamyka przystań kajakową władza.
  More marked or stylistic

Even when the order changes, władza is still the subject and przystań kajakową is still the object.

Because Polish has no articles.

So Polish does not normally use separate words corresponding to English a/an and the.

Whether something is understood as a kayak marina or the kayak marina depends on:

• context
• word order
• the broader situation

That is completely normal in Polish, and learners just get used to reading definiteness from context instead of from articles.