Opłata za przetrzymanie jest wysoka.

Because it agrees with opłata, which is a feminine singular noun.

• opłata = fee, charge
• feminine singular noun
• so the adjective must also be feminine singular:
  • wysoki = masculine
  • wysoka = feminine
  • wysokie = neuter

So Opłata ... jest wysoka literally means The fee ... is high, with both opłata and wysoka in the nominative feminine singular.

It is in the nominative case because it is the subject of the sentence.

In Opłata za przetrzymanie jest wysoka:

• opłata = the subject
• jest wysoka = says something about the subject

So this is a standard nominative subject + być + adjective structure.

Here za means for.

So:

• opłata za coś = a fee for something
• opłata za przetrzymanie = a fee for keeping something too long / an overdue fee

This is a very common Polish pattern:

• opłata za bilet = fee/payment for a ticket
• opłata za parking = parking fee
• opłata za usługę = fee for a service

Here za takes the accusative case.

So przetrzymanie is accusative here. However, przetrzymanie is a neuter noun, and for many neuter nouns the nominative and accusative singular look the same, so the form does not change.

That is why you see:

• nominative: przetrzymanie
• accusative: przetrzymanie

Same form, different function.

Przetrzymanie is a noun meaning something like keeping something too long, retaining something past the allowed time, or overdue keeping/retention depending on context.

It is formed from the verb przetrzymać, which can mean:

• to keep something longer than allowed
• to hold on to something too long
• sometimes more generally, to withstand or endure, depending on context

In this sentence, przetrzymanie most naturally refers to something like an overdue item, especially in contexts such as libraries or rentals.

It is a verbal noun.

Polish often creates nouns from verbs to express the act of doing something:

• czytać = to read → czytanie = reading
• pisać = to write → pisanie = writing
• przetrzymać = to keep too long → przetrzymanie = keeping too long / overdue retention

So opłata za przetrzymanie is literally something like a fee for the act of keeping something too long.

In a normal full sentence like this, jest is needed.

• jest = is
• Opłata za przetrzymanie jest wysoka = The overdue fee is high

Polish often omits subject pronouns like on, ona, ja, etc., but it does not normally omit the verb być in this kind of present-tense sentence.

You may sometimes see omission in:

• headlines
• notes
• very informal style

But in standard speech and writing, jest is the normal form here.

Not as a normal standard sentence.

It might appear in:

• headlines
• signs
• compressed informal notes

But if you are learning standard Polish, use:

• Opłata za przetrzymanie jest wysoka.

That is the safe and correct full sentence.

Yes, it is completely normal.

In Polish, prices, fees, costs, and rates are often described with wysoki / wysoka / wysokie:

• wysoka cena = a high price
• wysoka opłata = a high fee
• wysokie koszty = high costs

You could also hear words like duża in some contexts, but wysoka opłata is the most natural standard choice.

Yes, Polish word order is fairly flexible, although the neutral order here is:

• Opłata za przetrzymanie jest wysoka.

Other orders are possible for emphasis, for example:

• Wysoka jest opłata za przetrzymanie.
• Za przetrzymanie opłata jest wysoka.

But these sound more marked or stylistically shaped. For a learner, the original sentence is the best neutral pattern.

In neutral speech, the main stress often falls toward the end, especially on the new information:

• Opłata za przetrzymanie jest wysoka.

If the important information is that the fee is specifically high, then wysoka gets the strongest emphasis.

If you wanted contrast, you could stress another part:

• Opłata za przetrzymanie jest wysoka.
• Opłata za przetrzymanie jest wysoka.

But in an ordinary statement, the final adjective often carries the focus.

A rough pronunciation guide is:

• pshe-tshi-MA-nye

More carefully:

• prze sounds roughly like pshe
• trzy sounds roughly like tshi
• manie sounds roughly like MA-nye

The stress is on the second-to-last syllable:

• prze-trzy-MA-nie

This is normal in Polish: stress usually falls on the penultimate syllable.

It is a natural phrase, especially in contexts where something is kept longer than allowed, such as:

• a library book
• a rented item
• borrowed materials

It may be translated in English as:

• overdue fee
• late fee
• fee for keeping something too long

So even though the Polish wording is more literal, it works like a fairly standard expression.

Good question. They can overlap in meaning, but they are not exactly the same.

• opłata = fee, charge, payment
• kara = penalty, punishment, fine

So:

• opłata za przetrzymanie sounds like an official fee/charge for overdue keeping
• kara za przetrzymanie would sound more like a penalty or punishment

In many real-life situations, English might call both of these a fine or late fee, but Polish can frame it either as a charge or as a penalty depending on the institution and wording.

No, not only libraries, although that is one of the most common interpretations.

Depending on context, it could refer to:

• a library item kept past the due date
• a rented object returned late
• some other borrowed or retained item

So the sentence itself is general, but many learners will most naturally understand it as something like The overdue fee is high.