Tablica rejestracyjna jest czysta.

Tablica rejestracyjna is the subject, jest is the verb, and czysta is the adjective describing the subject.

So the structure is:

[subject] + [form of być / to be] + [adjective]

In other words, it works very much like The license plate is clean in English.

Because tablica rejestracyjna is the normal fixed expression for license plate / registration plate in Polish. Although adjectives often come before nouns in Polish, some established official or technical expressions place the adjective after the noun. This is one of those cases.

So learners should treat tablica rejestracyjna as a set phrase rather than trying to apply a simple word-order rule to every adjective.

Because they both agree with tablica, which is a feminine singular noun. In Polish, adjectives must match the noun in gender, number, and case.

Here:

• tablica is feminine singular
• rejestracyjna matches it
• czysta also matches it

That is why both adjectives have feminine singular endings.

It is in the nominative singular, because it is the subject of the sentence.

The adjective czysta is also in the nominative singular feminine, because after jest with an adjective, Polish normally uses an agreeing adjective form.

In a normal full sentence, jest is needed. It is the 3rd person singular present form of być, meaning to be.

So:

• Tablica rejestracyjna jest czysta. = normal, standard sentence

You may sometimes hear or see the verb omitted in very informal, note-like, or headline-style language, but that is not the neutral standard form. For a learner, it is best to use jest here.

You would say czysta tablica rejestracyjna.

Compare the two patterns:

• Tablica rejestracyjna jest czysta. = The license plate is clean.
• czysta tablica rejestracyjna = a clean license plate

So in the second version, czysta becomes part of the noun phrase rather than the predicate of the sentence.

Not exactly.

• tablica rejestracyjna = the physical plate
• numer rejestracyjny = the registration number

So Tablica rejestracyjna jest czysta makes literal sense because the plate itself can be clean. If you said Numer rejestracyjny jest czysty, that would sound odd in most normal contexts, because a number is not usually something you describe as physically clean.

It would become:

Tablice rejestracyjne są czyste.

The changes are:

• tablica → tablice
• rejestracyjna → rejestracyjne
• jest → są
• czysta → czyste

So the meaning is The license plates are clean.

Yes, Polish word order is more flexible than English, but different orders can sound more marked or emphatic.

The neutral order is:

Tablica rejestracyjna jest czysta.

You could also say something like Czysta jest tablica rejestracyjna, but that sounds more emphatic or stylistically marked. For everyday use, the original order is the safest and most natural one.

The dictionary forms are:

• tablica = board, plate
• rejestracyjny = registration-related
• być = to be
• czysty = clean

In the sentence, these appear in forms that match the grammar of the whole phrase:

• rejestracyjny → rejestracyjna
• być → jest
• czysty → czysta