Кабачок жовтий.

In Ukrainian, the verb to be is usually omitted in the present tense.

So:

• Кабачок жовтий = The zucchini is yellow

Literally, it looks like Zucchini yellow, but in natural Ukrainian this is a complete sentence.

If you wanted past or future, a form of бути would appear:

• Кабачок був жовтий = The zucchini was yellow
• Кабачок буде жовтий = The zucchini will be yellow

Yes, you can say both, but they do not work in exactly the same way.

• Кабачок жовтий is a full sentence: The zucchini is yellow
• жовтий кабачок is a noun phrase: a yellow zucchini / the yellow zucchini

So the difference is not just word order; it is also grammatical structure:

• noun + adjective here = predicate statement
• adjective + noun = adjective directly describing the noun inside one phrase

Compare:

• Кабачок жовтий. = The zucchini is yellow.
• Жовтий кабачок лежить на столі. = A yellow zucchini is lying on the table.

The ending -ий shows that the adjective agrees with кабачок.

Кабачок is:

• masculine
• singular
• nominative

So the adjective must also be:

• masculine
• singular
• nominative

That gives:

• жовтий

Some other forms of yellow are:

• жовтий — masculine singular
• жовта — feminine singular
• жовте — neuter singular
• жовті — plural

Examples:

• Лимон жовтий. = The lemon is yellow.
• Квітка жовта. = The flower is yellow.
• Сонце жовте. = The sun is yellow.
• Листки жовті. = The leaves are yellow.

Yes. Кабачок is a masculine noun.

A good clue is that it ends in a consonant, which is very common for masculine nouns in Ukrainian.

Because it is masculine, the adjective also takes the masculine form:

• кабачок жовтий

If the noun were feminine or neuter, the adjective would change:

• груша жовта = the pear is yellow
• яблуко жовте = the apple is yellow

Both words are in the nominative case.

That is because кабачок is the subject of the sentence, and жовтий is a predicate adjective agreeing with it.

So:

• кабачок = nominative singular
• жовтий = nominative singular masculine

This is the normal pattern for simple present-tense sentences like:

• Будинок великий. = The house is big.
• Чай гарячий. = The tea is hot.

It can mean either, depending on context.

Ukrainian has no articles like a or the, so the sentence itself does not mark that distinction.

So Кабачок жовтий could be understood as:

• The zucchini is yellow
• A zucchini is yellow

Usually the context tells you which one is meant.

This is very common in Ukrainian. For example:

• Стіл великий could mean The table is big or A table is big, depending on the situation.

The stress is:

• кабачо́к
• жо́втий

So the full sentence is pronounced approximately:

• ka-ba-CHOK ZHOV-tyi

A rough guide:

• ч sounds like ch in chat
• ж sounds like s in measure or zh
• ий in жовтий is not exactly like English ee; it is a Ukrainian vowel combination, often approximated by learners as yi

The stressed syllables are important, especially in кабачо́к.

Yes, grammatically it is completely normal.

However, in real conversation, people often use this kind of sentence only when they are:

• describing something
• contrasting it with another thing
• answering a question
• teaching vocabulary or grammar

For example:

• Який кабачок? — Кабачок жовтий. = What is the zucchini like? — The zucchini is yellow.

In many real-life situations, a speaker might prefer a fuller sentence depending on context, but Кабачок жовтий itself is perfectly natural Ukrainian.