القبعة وواقي الشمس في الحقيبة.

Yes. This is a complete Arabic sentence.

In present-tense Arabic, the verb to be is usually omitted. So instead of saying something equivalent to the hat and the sunscreen are in the bag, Arabic simply says:

القبعة وواقي الشمس في الحقيبة

This is called a nominal sentence.

• القبعة وواقي الشمس = the subject
• في الحقيبة = the predicate, telling where they are

English needs are here, but Arabic does not.

Because واقي الشمس is an iḍāfa construction, often called a possessive or noun-link construction.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun determines whether the whole phrase is definite

So:

• شمس = sun
• الشمس = the sun
• واقي الشمس = sunscreen / sun protector

Since الشمس is definite, the whole phrase واقي الشمس is definite too. So it can mean the sunscreen even though واقي itself does not have الـ.

It is an iḍāfa phrase made of two nouns:

• واقي = protector / guard / shield
• الشمس = the sun

So literally it is something like sun-protector or protector from the sun.

Very often, Arabic uses this kind of noun-noun structure where English might use:

• a compound noun
• of
• or another looser relationship

So واقي الشمس is the normal Arabic way to say sunscreen or sunblock.

Because ش is a sun letter.

In Arabic, when الـ comes before a sun letter, the l sound is not pronounced. Instead, the following consonant is doubled.

So:

• written: الشمس
• pronounced: ash-shams

This happens in pronunciation, not spelling. The spelling still keeps الـ.

Normally it applies to both.

The sentence is understood as:

• the hat and the sunscreen are in the bag

Arabic, like English, allows one location phrase to apply to two coordinated nouns joined by و.

If a speaker wanted to say that only the second item was in the bag, they would usually need a different structure or clearer wording.

الحقيبة is definite because it means the bag, a specific or known bag.

• في الحقيبة = in the bag
• في حقيبةٍ = in a bag

So the presence or absence of الـ changes whether the noun is definite or indefinite.

In careful fully inflected MSA, you could analyze it as:

القُبَّعَةُ وواقي الشَّمْسِ في الحَقيبَةِ

Here is why:

• القبعةُ is nominative because it is part of the subject
• واقي is also nominative as part of the coordinated subject
• الشمسِ is genitive because it is the second term of the iḍāfa
• الحقيبةِ is genitive because it comes after في

One important detail: واقي is a type of noun whose final case ending is often not visibly pronounced in the nominative and genitive, so learners may not see an obvious ending there.

A careful pronunciation is:

al-qubbaʿatu wa-wāqī ash-shamsi fī al-ḥaqībati

If you are reading in normal pause style, without emphasizing full case endings, it may sound closer to:

al-qubbaʿa wa-wāqī ash-shams fī al-ḥaqība

A few helpful points:

• ق in القبعة and الحقيبة is a deep q sound
• ʿ in قبعة represents ع
• ḥ in حقيبة is a stronger h sound
• الشمس is pronounced ash-shams, not al-shams

Yes, Arabic can change the order for style, rhythm, or emphasis.

For example, you could put the location first:

في الحقيبة القبعة وواقي الشمس

That can sound more like In the bag are the hat and the sunscreen.

But the original order, القبعة وواقي الشمس في الحقيبة, is straightforward and very natural for learners to understand.

Grammatically, it is singular.

Even though English often uses sunscreen as a mass noun, Arabic commonly uses the singular expression واقي الشمس for the product in general.

So in this sentence, it refers to one sunscreen item or one sunscreen product understood as a single thing. If you wanted a clearly plural meaning, you would need a different form or a different phrasing.