Pravidla jsou známá.

That is a very common confusion.

Pravidla is the nominative plural of pravidlo (rule).
Pravidlo is a neuter noun, and many neuter nouns in Czech form the plural with -a:

• město → města
• okno → okna
• pravidlo → pravidla

So even though -a may look singular to an English speaker, here it is a normal neuter plural ending.

One extra detail: pravidla can also be genitive singular in other contexts, but in this sentence it is clearly plural because the verb is jsou (are), not je (is).

Jsou is the 3rd person plural present-tense form of být (to be).

So:

• je = is
• jsou = are

Because pravidla is plural, Czech uses jsou.

Because the adjective has to agree with pravidla.

In Czech, adjectives match the noun in:

• gender
• number
• case

Here:

• pravidla = neuter plural nominative
• so známý must become známá

This is the normal nominative plural ending for many neuter adjectives.

Compare:

• známý muž = a known man
• známá žena = a known woman
• známé město = a known town
• známá pravidla = known rules

So známá is correct because the subject is neuter plural.

Yes.

After být (to be), Czech commonly uses a predicate adjective in the nominative. So both the subject and the adjective are in nominative, and the adjective agrees with the subject.

That is why:

• Pravidla jsou známá.

uses nominative plural pravidla and nominative plural známá.

The biggest clue is the agreement.

• jsou is plural
• známá is neuter plural
• both match pravidla

So pravidla is the subject: the rules.

This matters because pravidla by itself could have more than one grammatical role in other sentences, but here the verb and adjective make its function clear.

Normally, no. In standard Czech, you should keep jsou.

So the normal sentence is:

• Pravidla jsou známá.

Leaving it out would sound incomplete in ordinary speech, though you might sometimes see omission in headlines, notes, or very stylized writing.

Unlike some other Slavic languages, Czech normally keeps the present-tense forms of být.

No. Czech has no articles like English a or the.

So Pravidla jsou známá can mean something like:

• The rules are known
• Rules are known

Which one is intended depends on context. In most normal situations, the context tells you whether English should use the.

Yes. Czech word order is flexible, although the basic neutral order here is:

• Pravidla jsou známá.

You could also see:

• Známá jsou pravidla.

That version is less neutral and changes the emphasis. Czech often uses word order to highlight what is new, important, or contrasted.

So for a basic textbook sentence, Pravidla jsou známá is the most straightforward form.

The dictionary form is známý.

Czech adjectives are usually listed in the masculine singular nominative form, so:

• dictionary form: známý
• in this sentence: známá

That change happens because it agrees with pravidla.

Approximate pronunciation:

• Pravidla ≈ PRA-vid-la
• jsou ≈ ysoh
• známá ≈ ZNAA-maa

Important stress rule: Czech normally stresses the first syllable of each word.

So the main word stresses are:

• PRA-vid-la
• jsou
• ZNÁ-má

Also note:

• á is a long vowel
• ou in jsou is a diphthong
• z in známá is pronounced normally; the word begins with a real zn- cluster