Poplatek je vysoký.

Je is the 3rd person singular present tense of být (to be).

So:

• já jsem = I am
• ty jsi = you are
• on/ona/ono je = he/she/it is

In Poplatek je vysoký, je means is.

Because vysoký is an adjective, and in Czech adjectives must agree with the noun they describe.

Poplatek is:

• singular
• masculine
• inanimate
• nominative

So the adjective also takes the nominative singular masculine inanimate form: vysoký.

Compare:

• poplatek je vysoký = the fee is high
• cena je vysoká = the price is high
  (cena is feminine, so the adjective changes to vysoká)
• nájemné je vysoké = the rent is high
  (nájemné is neuter, so the adjective changes to vysoké)

Yes. Poplatek is a masculine inanimate noun.

A useful clue is that many Czech nouns ending in a consonant are masculine. Here it is specifically masculine inanimate, not animate.

That matters because adjectives and some other words must match it:

• vysoký poplatek
• ten poplatek = that fee

Yes, vysoký often means tall or high, but it is also commonly used for amounts, levels, prices, fees, and similar things.

So in this sentence, vysoký means high, not tall.

Examples:

• vysoká cena = a high price
• vysoký plat = a high salary
• vysoký poplatek = a high fee

This is very similar to English, where we also say a high fee.

Usually Poplatek je vysoký is the more natural choice.

Why?

• vysoký is commonly used for prices, fees, rates, amounts
• drahý means expensive

A fee is more naturally described as high than expensive in Czech.
So Poplatek je vysoký sounds more standard.

Czech does not have articles like English a and the.

So Poplatek je vysoký can mean:

• The fee is high
• A fee is high

In real use, the context tells you which meaning is intended. Very often, English needs an article, but Czech simply does not use one.

They are both in the nominative.

• Poplatek is the subject of the sentence.
• Vysoký is a predicate adjective after je, and in this kind of sentence it also stays in the nominative.

So this is a basic nominative sentence structure:

• Noun + být + adjective

Example pattern:

• Dům je velký. = The house is big.
• Poplatek je vysoký. = The fee is high.

Normally, in a full standard sentence like this, no.

You should say:

• Poplatek je vysoký.

Leaving out je would sound incomplete in normal speech and writing. You may sometimes see the verb omitted in headlines, notes, or very informal styles, but for learners the correct full sentence is:

• Poplatek je vysoký.

The neutral, standard word order is:

• Poplatek je vysoký.

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

For example:

• Poplatek je vysoký. = neutral statement
• Vysoký je poplatek. = marked or unusual; emphasizes high
• Je vysoký poplatek. = possible in special contexts, but not the basic version learners should use

So for normal use, stick with:

• Poplatek je vysoký.

A rough English-friendly guide is:

• Poplatek ≈ PO-plah-tek
• je ≈ ye
• vysoký ≈ VI-soh-kee

A few helpful notes:

• j in Czech is pronounced like English y in yes
• y in vysoký is not exactly the same as English ee, but kee is a useful approximation
• the long ý is held a bit longer than a short vowel

So the whole sentence sounds roughly like:

PO-plah-tek ye VI-soh-kee

In Czech, stress normally falls on the first syllable of each word.

So:

• POplatek
• je
• VYsoký

That means the main word stress is:

PO-pla-tek je VY-so-ký

This is much more regular than English stress, which is good news for learners.

The dictionary forms are:

• poplatek = fee, charge
• být = to be
• vysoký = high, tall

In this sentence:

• poplatek is already in its dictionary form
• je is a conjugated form of být
• vysoký is the masculine singular nominative form, which is also the dictionary form for this adjective

Not exactly.

• poplatek = fee, charge, payment for a service or administrative action
• cena = price

So for example:

• Poplatek za parkování = parking fee
• Cena auta = the price of the car

In your sentence, poplatek specifically refers to a fee or charge, not just any price.