Pojistná částka pro léčebné výlohy je vysoká.

A useful breakdown is:

• pojistná = adjective, feminine singular, nominative
• částka = noun, feminine singular, nominative
• pro = preposition meaning for
• léčebné = adjective, feminine plural, accusative
• výlohy = noun, feminine plural, accusative
• je = is
• vysoká = adjective, feminine singular, nominative, used as the predicate adjective (high)

So the structure is basically:

• [Pojistná částka] = the subject
• [pro léčebné výlohy] = a prepositional phrase modifying částka
• [je vysoká] = is high

Because it agrees with částka, which is:

• feminine
• singular
• nominative

In Czech, adjectives must agree with the noun they describe in gender, number, and case.

So:

• pojistný = basic dictionary form (masculine singular)
• pojistná = feminine singular form

Since částka is a feminine noun, you get pojistná částka.

It is both a normal adjective + noun combination and also a common insurance term.

• částka = amount, sum
• pojistná částka = insured sum / sum assured / insurance amount

In real-life Czech, this is a standard phrase used in insurance contexts.

A learner may also wonder about pojištěná částka. That is not the usual term here.
The standard term is pojistná částka.

The preposition pro takes the accusative case.

So:

• pro koho? pro co? = for whom? for what?

Here, the noun phrase after pro is:

• léčebné výlohy = medical expenses / treatment expenses

This whole phrase is in the accusative plural.

Because after pro, Czech uses the accusative, not the genitive.

The noun výlohy here is plural.
Its accusative plural form is výlohy.

The adjective has to match it, so:

• nominative plural feminine: léčebné výlohy
• accusative plural feminine: léčebné výlohy

For feminine plural nouns, the nominative and accusative often look the same, which is why you see léčebné výlohy here.

If it were singular, you would clearly see the accusative more easily:

• pro léčebnou výlohu = for a medical expense

Because the subject of the sentence is pojistná částka, not léčebné výlohy.

The phrase pro léčebné výlohy is only extra information telling you what the amount is for.

So the agreement is with:

• částka = feminine singular

That is why you get:

• je = singular is
• vysoká = feminine singular high

A good way to see it is:

• Pojistná částka ... je vysoká.
• For medical expenses is just inserted into the middle.

Because vysoká is a predicate adjective after je (is), and it agrees with the subject:

• částka = feminine singular
• therefore vysoká = feminine singular

Czech does this very consistently:

• částka je vysoká = the amount is high
• limit je vysoký = the limit is high
• ceny jsou vysoké = the prices are high

Yes. In Czech, vysoký / vysoká / vysoké is commonly used for things like:

• prices
• amounts
• salaries
• costs
• limits

So vysoká částka is perfectly natural and means a high amount.

This is similar to English, where we also say:

• a high price
• a high amount
• high expenses

Because Czech has no articles like English the and a/an.

So pojistná částka can mean, depending on context:

• the insurance amount
• an insurance amount
• the insured sum

Context tells you which one is meant.

This is very normal in Czech, and learners simply have to get used to reading definiteness from context instead of from an article.

The given order is the most neutral and natural:

• Pojistná částka pro léčebné výlohy je vysoká.

Czech word order is more flexible than English, but changing it changes the emphasis.

For example:

• Pro léčebné výlohy je pojistná částka vysoká.
  This puts more focus on for medical expenses.

The original sentence is the best neutral version for a textbook or standard statement.

A simple learner-friendly pronunciation guide is:

PO-jist-ná CHÁST-ka pro LÉ-cheb-né VÝ-lo-hy ye VY-so-ká

A few useful notes:

• Czech stress is usually on the first syllable of each word.
• č sounds like ch in chip
• j sounds like English y
• á and é are long vowels
• ch in léčebné is not like English ch; it is the Czech ch sound, like a rough h / German Bach

So je sounds roughly like ye.