kono kussyonkabaa ha utukusii.

When は is used as a particle, it is pronounced wa, not ha. In this sentence, は marks the topic of the sentence:

• この クッションカバー は 美しい。
• As for this cushion cover, it is beautiful.

So although it is written は, you say wa.

この means this, but it must be used together with a noun. So:

• この クッションカバー = this cushion cover

You cannot use この by itself. If you want to say this alone, you use これ instead.

Compare:

• このクッションカバー = this cushion cover
• これ = this

クッションカバー is a loanword, based on English cushion cover, so it is written in katakana, which is commonly used for foreign-derived words.

Its pronunciation is adapted to Japanese sound patterns, so it sounds more like:

• kusshon kabaa

This is very common in Japanese vocabulary.

There is no です because this sentence is in the plain style.

Also, 美しい is an i-adjective, and i-adjectives can end a sentence by themselves:

• このクッションカバーは美しい。

If you want to make it more polite, you can say:

• このクッションカバーは美しいです。

Both are grammatical. The version without です sounds plain; the version with です sounds polite.

美しい is an i-adjective meaning beautiful.

In Japanese, i-adjectives can directly describe a noun or finish a sentence:

• Before a noun: 美しい花 = a beautiful flower
• At the end of a sentence: 花は美しい。 = The flower is beautiful.

So in your sentence, 美しい is the predicate: it tells us what the cushion cover is like.

Yes, it is grammatical and understandable, but it may sound a little elevated, literary, or formal depending on context.

For everyday conversation, Japanese speakers might also use words like:

• きれい = pretty / beautiful / clean-looking
• かわいい = cute

So:

• このクッションカバーは美しい。 sounds somewhat refined or descriptive.
• このクッションカバーはきれいです。 may sound more everyday in many situations.

Still, 美しい is absolutely correct.

The basic structure is:

• この クッションカバー = this cushion cover
• は = topic marker
• 美しい = is beautiful

So the overall pattern is:

• [topic] は [comment]

A very literal gloss would be:

• As for this cushion cover, [it] is beautiful.

This topic-comment structure is extremely common in Japanese.

Using は presents this cushion cover as the topic and says something about it.

• このクッションカバーは美しい。
  • As for this cushion cover, it is beautiful.

If you use が instead:

• このクッションカバーが美しい。

that can sound more like:

• This cushion cover is the beautiful one
• or It is this cushion cover that is beautiful

So は is more neutral for a simple description, while が often adds focus or contrast, depending on context.

No. Normally, Japanese is written without spaces:

• このクッションカバーは美しい。

The spaced version is often used in beginner materials to make the parts easier to read. In natural Japanese text, you would usually not see spaces like this.

Yes. Japanese adjectives can directly modify nouns.

So you can say:

• この美しいクッションカバー = this beautiful cushion cover

But that is not exactly the same structure as the original sentence.

Compare:

• このクッションカバーは美しい。

  • This cushion cover is beautiful.

• この美しいクッションカバー

  • this beautiful cushion cover

The first is a full sentence. The second is just a noun phrase.

The easiest way is:

• このクッションカバーは美しいです。

That keeps the meaning the same but makes the tone more polite.

You could also choose a more conversational adjective if appropriate, for example:

• このクッションカバーはきれいです。

That may sound more natural in everyday speech, depending on what kind of beauty you want to express.