Воздушно-пузырчатая плёнка защищает очки.

Literally, it means something like air-bubbly film:

• воздушно- = air-related
• пузырчатая = bubbly, full of bubbles
• плёнка = film, sheet, thin plastic layer

Together, this is the standard Russian term for bubble wrap.

It is a compound adjective. Russian often uses a hyphen when two descriptive elements are joined into one adjective.

Here, the idea is roughly:

• воздушно- = air-
• пузырчатая = bubble-like / bubbly

So the whole adjective acts as one unit modifying плёнка.

Because it agrees with плёнка.

In Russian, adjectives must match the noun they describe in:

• gender
• number
• case

Here, плёнка is:

• feminine
• singular
• nominative

So the adjective also takes the feminine singular nominative ending -ая:

• воздушно-пузырчатая плёнка

защищает is:

• 3rd person singular
• present tense
• from the verb защищать = to protect, to defend

It matches the subject плёнка, which is singular. So the sentence structure is:

• плёнка защищает = the film protects

Depending on context, Russian present tense can also express a general truth, so it can mean protects or is protecting.

Because очки is the object, not the subject.

The subject is плёнка, and Russian verbs agree with the subject, not with the object.

So:

• плёнка = singular subject
• защищает = singular verb
• очки = plural object

English works the same way here: Bubble wrap protects glasses, not Bubble wrap protect glasses.

It is in the accusative plural, because it is the direct object of защищает.

However, for inanimate plural nouns, the accusative often looks exactly like the nominative. So:

• nominative: очки
• accusative: очки

That is why the form does not change.

Russian treats очки as a plural-only noun in normal usage, much like English glasses.

So:

• очки = glasses / a pair of glasses

If you want to emphasize one pair, you can say:

• пара очков = a pair of glasses

Notice that after пара, the word changes form to очков.

Russian does not have articles like English a and the.

So плёнка can mean:

• film
• the film
• a film

and очки can mean:

• glasses
• the glasses

Which meaning is intended depends on context.

Yes. Russian word order is fairly flexible because grammatical endings show the relationships between words.

The neutral order here is:

• Воздушно-пузырчатая плёнка защищает очки.

But you could also say:

• Очки защищает воздушно-пузырчатая плёнка.

That version puts more emphasis on очки. The basic meaning stays the same, but the focus changes.

защищает comes from the imperfective verb защищать.

That matters because imperfective verbs are commonly used for:

• ongoing actions
• repeated actions
• general facts

So this sentence sounds like a general statement: bubble wrap protects glasses.

The perfective partner is usually защитить, which would be used for a completed result, for example:

• плёнка защитит очки = the wrap will protect the glasses / will succeed in protecting them

The stress is:

• воздУшно-пузЫрчатая
• плЁнка
• защищАет
• очкИ

So the full sentence is:

• воздУшно-пузЫрчатая плЁнка защищАет очкИ

Stress is very important in Russian, because it is not always predictable and can affect pronunciation quite a lot.