השמלה האדומה יפה, אבל אני רוצה לקנות לה חגורה חדשה.

In Hebrew, the verb to be is usually left out in the present tense.

So:

• השמלה האדומה יפה = The red dress is beautiful

Hebrew does not normally need a separate word for is here.

In other tenses, Hebrew does use forms of היה:

• השמלה האדומה הייתה יפה = The red dress was beautiful
• השמלה האדומה תהיה יפה = The red dress will be beautiful

You may sometimes see היא added for emphasis, but in a simple sentence like this it is normally omitted.

Because in Hebrew, adjectives usually come after the noun.

So:

• שמלה אדומה = a red dress
• literally: dress red

This is the normal Hebrew order for descriptive adjectives.

Because in Hebrew, an adjective that directly describes a noun must match the noun in definiteness.

Here, השמלה means the dress, so the adjective must also be definite:

• השמלה האדומה = the red dress

Compare:

• שמלה אדומה = a red dress
• השמלה האדומה = the red dress

This is a very important Hebrew pattern: when a noun is definite, its following adjective is also definite.

Because יפה here is not attached directly to the noun inside a noun phrase. It is the predicate adjective of the sentence:

• השמלה האדומה יפה = The red dress is beautiful

In this structure, Hebrew does not put ה־ on the adjective.

Compare:

• השמלה היפה = the beautiful dress
  
  • here יפה is directly modifying the noun
• השמלה יפה = the dress is beautiful
  
  • here יפה is the predicate, so no ה־

That difference is very common in Hebrew.

This is a great question, because unpointed Hebrew spelling hides some differences.

The adjective יפה can represent:

• יָפֶה = yafé = masculine singular
• יָפָה = yafá = feminine singular

Without vowel marks, both are written יפה.

Since שמלה is feminine, the word here is understood as יָפָה = feminine singular.

So the agreement is correct — it just is not obvious from the spelling alone.

Because, again, unpointed Hebrew spelling hides the vowel difference.

רוצה can be:

• רוֹצֶה = rotse = masculine singular
• רוֹצָה = rotsa = feminine singular

So אני רוצה can mean either:

• I want — said by a man
• I want — said by a woman

You know which one it is from context or pronunciation, not from the plain spelling alone.

Here לה means to her / for her, referring back to השמלה.

So:

• לקנות לה חגורה חדשה = to buy a new belt for it / for her

Since שמלה is a feminine noun, Hebrew uses the feminine pronoun לה.

Even though a dress is an object in English, Hebrew still treats it with grammatical gender, so using לה is completely normal.

Because לה and אותה do different jobs.

• לה = to her / for her = indirect object
• אותה = her / it = direct object

In this sentence, the thing being bought is חגורה חדשה — a new belt.
The dress is not the thing being bought; it is the thing the belt is for.

So:

• אני רוצה לקנות לה חגורה חדשה = I want to buy her/it a new belt / buy a new belt for it
• אני רוצה לקנות אותה = I want to buy it

That would mean buying the dress itself, which is a different meaning.

Because את is used only before a definite direct object.

Here, חגורה חדשה means a new belt, which is indefinite, so there is no את.

Compare:

• אני רוצה לקנות חגורה חדשה = I want to buy a new belt
• אני רוצה לקנות את החגורה החדשה = I want to buy the new belt

So the absence of את tells you the object is indefinite.

Because the adjective must agree with the noun in gender and number.

• חגורה is feminine singular
• so the adjective must also be feminine singular: חדשה

Compare:

• חגורה חדשה = a new belt
• ספר חדש = a new book

So חדש is masculine singular, while חדשה is feminine singular.

Yes, absolutely.

Both are natural, but they do slightly different things stylistically:

• לקנות לה חגורה חדשה = buy it/her a new belt
  
  • uses a pronoun, since the dress was just mentioned
• לקנות חגורה חדשה לשמלה = buy a new belt for the dress
  
  • repeats the noun more explicitly

Once השמלה has already been mentioned, לה is often the smoother and more natural choice.

Because אבל means but, and it shows a contrast:

• The red dress is beautiful, but I want to buy it a new belt

The idea is that the dress is already nice, however the speaker still wants to add something to it.

Without אבל, the connection would feel more like simple addition rather than contrast.