אני רוצה לצבוע את הקיר בחדר בצבע לבן, אבל היא רוצה קיר כחול.

In unpointed Hebrew, some masculine and feminine present-tense forms are spelled the same.

Here, רוצה can be read as:

• rotze for a masculine subject
• rotza for a feminine subject

So:

• אני רוצה can mean I want, said by either a man or a woman; the pronunciation depends on the speaker
• היא רוצה is definitely feminine, so it is pronounced rotza

If vowel points were written, the difference would be clearer:

• masculine: רוֹצֶה
• feminine: רוֹצָה

The ל־ here marks the infinitive, so לצבוע means to paint.

After רוצה (want/wants), Hebrew normally uses an infinitive:

• אני רוצה לצבוע = I want to paint

This is similar to English want to paint. So ל־ in this case is not the preposition to in a directional sense; it is part of the infinitive form.

את marks a definite direct object.

• את הקיר = the wall as a direct object
• קיר כחול = a blue wall, which is indefinite

So:

• אני רוצה לצבוע את הקיר = I want to paint the wall
• היא רוצה קיר כחול = She wants a blue wall

Hebrew uses את only before definite direct objects, usually ones with ה־ (the) or with other definite marking.

The prefix ב־ is very flexible. Its basic meaning is often in, but in real Hebrew it can also mean with, by, or in the form of, depending on context.

In this sentence:

• בחדר = in the room
• בצבע לבן = literally in white color, more naturally with white paint / in white

So the same prefix appears twice, but the full phrase determines the meaning.

This is very common in Hebrew. Prepositions do not always match English one-for-one.

The structure is different in the two parts.

In בצבע לבן, the adjective לבן describes צבע:

• צבע = color
• לבן = white in the masculine singular form

Since צבע is a masculine singular noun, the adjective is masculine singular too.

In קיר כחול, the adjective כחול describes קיר:

• קיר = wall
• כחול = blue in the masculine singular form

Again, קיר is masculine singular, so כחול is masculine singular.

If the noun were feminine, the adjective would change, for example:

• דלת כחולה = a blue door
• מכונית לבנה = a white car

Yes, לצבוע את הקיר בלבן is completely natural Hebrew.

Both mean essentially the same thing:

• בלבן = white / in white
• בצבע לבן = in white color / with white paint

The version with בצבע is a little more explicit and slightly fuller in wording. The shorter בלבן is very common in everyday speech.

So both are fine:

• לצבוע את הקיר בלבן
• לצבוע את הקיר בצבע לבן

Hebrew often leaves out repeated words when they are easy to understand from context.

So:

• אבל היא רוצה קיר כחול literally means but she wants a blue wall
• In context, it clearly implies she wants the wall to be blue or she wants to paint the wall blue

This is natural and efficient. English does the same kind of thing sometimes:

• I want to paint the wall white, but she wants a blue wall.

If you repeated everything, it would also be grammatical, but less compact:

• אבל היא רוצה לצבוע את הקיר בכחול

Because קיר כחול is indefinite: a blue wall, not the blue wall.

Compare:

• את הקיר = the wall
• קיר כחול = a blue wall

So the contrast is:

• I want to paint the wall...
• but she wants a blue wall

In context, this often means she wants the existing wall to end up blue, but grammatically the phrase itself is indefinite.

As written, בחדר most naturally goes with הקיר, so most learners will understand it as the wall in the room.

So the phrase is understood as:

• את הקיר בחדר = the wall in the room

But Hebrew can sometimes leave small attachment ambiguities like this, just as English can.

If you wanted to make it clearer, you could say:

• את הקיר שבחדר = the wall that is in the room

That version more explicitly attaches in the room to the wall.