Стретч-плёнка защищает мебель.

Стретч-плёнка means stretch film or plastic wrap used for packing/protecting things.

A few useful notes:

• стретч is a borrowing from English stretch
• плёнка means film or thin plastic film
• Together, стретч-плёнка is the kind of plastic wrap often used when moving or storing furniture

So in this sentence, it refers to packing wrap that protects furniture.

Russian often uses a hyphen in compound nouns when one part is a borrowed modifier and the whole expression works like a single noun.

So:

• стретч-плёнка
• literally: stretch-film

This is just the standard written form of this compound noun. You should learn it as one vocabulary item.

A rough pronunciation guide:

• стретч-плёнка → STRECH-PLYON-ka
• защищает → za-shi-SHCHA-yet
• мебель → MYE-belʹ

Stress:

• стретч-плёнка
• защищает
• мебель

A few pronunciation points:

• ё is pronounced yo
• щ in modern Russian is usually a long soft sh sound, often approximated as shch
• the final ь in мебель is a soft sign; it does not make its own sound, but it softens the preceding consonant

Because the subject, стретч-плёнка, is singular.

• стретч-плёнка = one thing
• so the verb must also be singular: защищает = protects

Compare:

• Стретч-плёнка защищает мебель. = Stretch film protects the furniture / furniture.
• Стретч-плёнки защищают мебель. = Stretch films protect furniture.

So защищает is the 3rd person singular form of защищать.

Защищает is:

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

Conjugation:

• я защищаю
• ты защищаешь
• он / она / оно защищает
• мы защищаем
• вы защищаете
• они защищают

In this sentence, it can be understood as:

• protects
• is protecting
  depending on context, since Russian present tense can cover both simple present and present continuous meanings.

Мебель is in the accusative case, because it is the direct object of the verb защищает.

The thing doing the action:

• стретч-плёнка = subject, nominative

The thing receiving the action:

• мебель = object, accusative

Why does мебель look unchanged?
Because for many inanimate nouns, the accusative has the same form as the nominative.

So:

• nominative: мебель
• accusative: мебель

No visible change, but it is still functioning as the accusative here.

Grammatically, мебель is singular.

But its meaning is often collective, like English furniture. It usually refers to furniture in general, not just one item.

So:

• мебель = furniture
• not usually a single piece of furniture

If you want to refer to one item, Russian often uses expressions like:

• предмет мебели = a piece of furniture

This is similar to English, where furniture is also not normally used as a countable singular noun.

Russian has no articles.

So Russian does not use words equivalent to a, an, or the.

That means:

• Стретч-плёнка защищает мебель
  can mean
• Stretch film protects furniture
• The stretch film protects the furniture
• A stretch film protects furniture

The exact meaning depends on context.

Yes. Russian word order is more flexible than English because case endings help show grammatical roles.

The neutral, straightforward order here is:

• Стретч-плёнка защищает мебель.

You could also see:

• Мебель защищает стретч-плёнка.

This still means Stretch film protects furniture, because стретч-плёнка is nominative and мебель is accusative. But the changed order gives different emphasis, for example highlighting мебель first.

So the original sentence is the most neutral and natural basic order.

The correct spelling is плёнка with ё.

• ё is a separate letter
• it is pronounced yo

However, in everyday writing, Russians often write е instead of ё, so you may also see:

• пленка

But the pronunciation is still usually understood as плёнка.

For learners, it is helpful to remember the correct form with ё, because it tells you the stress and pronunciation more clearly.

Yes. Защищать is imperfective.

In this sentence, the imperfective verb fits well because it describes a general function or ongoing action:

• Стретч-плёнка защищает мебель.
• Stretch film protects furniture.

The perfective partner is usually защитить.

A perfective form would shift the meaning toward a completed result. For example:

• Стретч-плёнка защитит мебель. = The stretch film will protect the furniture.

So:

• защищает = general, ongoing, habitual protection
• защитит = future, completed protection/result