Peřej je před jezem.

Because peřej is grammatically singular, so the verb být takes the 3rd person singular form je.

• peřej je = the rapid / the stretch of rapids is
• peřeje jsou = the rapids are

This can feel strange to an English speaker because English often uses rapids as a plural noun.

Yes. Peřej is a singular feminine noun.

A useful thing to remember is:

• singular: peřej
• plural: peřeje

So in this sentence, Czech is treating it as one rapid / one stretch of rough water, not as a plural set.

Because the preposition před requires the instrumental case here.

So:

• dictionary form: jez
• after před: jezem

That is why the sentence says před jezem, not před jez.

This is a very common Czech pattern: a preposition determines the case of the noun that follows it.

Here před means in front of / before in a spatial sense.

So the sentence describes location: the rapid is located before the weir.

Depending on context, in natural English you might think of it as:

• in front of the weir
• before the weir
• upstream from the weir

The exact English wording depends on the situation, but grammatically Czech is using před to show position relative to something else.

Peřej is in the nominative case, because it is the subject of the sentence.

You can break the sentence down like this:

• Peřej = subject
• je = verb
• před jezem = prepositional phrase describing location

So the basic structure is: subject + is + location.

Because Czech does not have articles like English a/an and the.

So peřej can mean:

• a rapid
• the rapid

and jez can mean:

• a weir
• the weir

The exact meaning is understood from context, not from an article.

Yes. Czech word order is more flexible than English word order.

For example, these are possible:

• Peřej je před jezem.
• Před jezem je peřej.

Both are grammatical. The difference is mostly in focus or emphasis, not basic meaning.

The original sentence is a neutral, straightforward way to say it.

The stress is on the first syllable, as usual in Czech:

• PE-řej

The hardest part for English speakers is ř, which is a special Czech sound with no exact English equivalent. It sounds a bit like a mix of r and zh.

A rough approximation for learners might be:

• peřej ≈ PEH-rzhay

That is only approximate, but it may help at first.

A rough learner-friendly pronunciation is:

PEH-rzhay yeh PRZHET YEH-zem

A few notes:

• Czech stress is on the first syllable of each word.
• před contains ě, but you do not need to overthink it at first.
• The biggest challenge is again ř in peřej and před.

If you want to sound more natural, focus especially on:

• short, clear vowels
• first-syllable stress
• practicing ř

Jez is a masculine inanimate noun meaning weir—a low barrier built across a river to control water flow.

Its declension in the singular includes:

• nominative: jez
• instrumental: jezem

That is why after před you get před jezem.

You would say:

Peřeje jsou před jezem.

Changes:

• peřej → peřeje (plural)
• je → jsou (plural verb)

The phrase před jezem stays the same, because it still means before the weir and jez is still singular instrumental after před.