قبعة السباحة زرقا.

A common Levantine-style pronunciation would be something like 'obbaʿet is-sbāḥa zar'a.

A few notes:

• ق in قبعة may be pronounced as q in some areas, but in many urban Levantine accents it becomes a glottal stop, so qubbaʿet or 'obbaʿet are both possible depending on region.
• The ة in قبعة is not just -a here; because the word is linked to the next noun, it is pronounced more like -et or -it.
• ال in السباحة is not fully pronounced as al- here, because س is a sun letter, so the l merges into the s sound.

So you may hear slightly different versions, but that general shape is what to expect.

Because Arabic often leaves out the present-tense to be.

So in Levantine:

• قبعة السباحة زرقا = The swimming cap is blue

There is no separate word for is in a simple present-tense sentence like this.

But in other tenses, Arabic does use a verb:

• كانت زرقا = it was blue
• رح تكون زرقا = it will be blue

This is one of the most common sentence patterns in Arabic: subject + description.

It is an iḍāfa construction, often called a construct phrase.

Literally, it is something like:

• قبعة = cap
• السباحة = swimming

So together it means swimming cap, literally cap of swimming.

This is very common in Arabic. Instead of making one noun act like an adjective, Arabic often links two nouns together.

Examples of the same idea:

• باب البيت = the door of the house
• كتاب الطالب = the student’s book
• قبعة السباحة = the swimming cap

Because of the ة at the end, called tāʾ marbūṭa.

When a word ending in ة stands alone, it is usually pronounced with a final -a sound:

• قبعة by itself ≈ qubbaʿa / 'obbaʿa

But when that word is followed by another noun in an iḍāfa construction, the ة is pronounced as t:

• قبعة السباحة ≈ qubbaʿet is-sbāḥa

So this change is normal and expected.

Because س is a sun letter.

In Arabic, when ال comes before a sun letter, the l sound assimilates into the next consonant. So:

• السباحة is pronounced more like is-sbāḥa or es-sbāḥa
• not a careful al-sibāḥa

This happens with many letters, for example:

• الشمس → ash-shams
• السماء → as-sama
• السباحة → is-sbāḥa / es-sbāḥa

In writing, the ال stays the same. The change is in pronunciation.

Because Arabic normally places adjectives after the noun, not before it.

In this sentence, the descriptive word زرقا comes after the subject:

• قبعة السباحة زرقا

That matches normal Arabic word order for this kind of sentence.

English says:

• The swimming cap is blue

Arabic says more like:

• The swimming cap blue

So even though the word order feels unusual to an English speaker, it is completely normal in Arabic.

Because قبعة is a feminine noun, and adjectives in Arabic agree with the noun they describe.

The masculine and feminine forms are different:

• masculine: أزرق
• feminine: زرقا in Levantine spelling/pronunciation

Since قبعة is feminine, the sentence uses the feminine form:

• قبعة السباحة زرقا

If the noun were masculine, you would use the masculine adjective instead.

Because this is a Levantine-style colloquial spelling.

In Modern Standard Arabic, the feminine form is usually written:

• زرقاء

In Levantine everyday writing, people often write it in a simpler colloquial way as:

• زرقا

Both point to the same feminine adjective blue, but زرقا better reflects how it is often said in speech.

So:

• زرقاء = more standard/formal spelling
• زرقا = common colloquial Levantine-style spelling

Because here زرقا is the predicate of the sentence, not part of the noun phrase.

That distinction matters:

• قبعة السباحة زرقا = The swimming cap is blue
• قبعة السباحة الزرقا = the blue swimming cap

So if you add ال to the adjective, it stops sounding like the main description of the sentence and starts sounding like part of the noun phrase itself.

This is a very important pattern in Arabic:

• definite noun + adjective without ال often gives a full sentence
• definite noun + adjective with ال gives a noun phrase

Yes, it is understandable and correct, but it can sound a little more neutral or standard-like than the most casual everyday speech.

In very colloquial Levantine, some speakers might also say كاب for cap, especially in modern everyday conversation.

So you might hear things like:

• قبعة السباحة زرقا
• كاب السباحة زرقا

The sentence you were given is perfectly useful for learning, and people will understand it. Just be aware that spoken Levantine often mixes native vocabulary with borrowed everyday words.