Ta firanka jest ładna, ale chcę postawić drugi regał bliżej biurka.

Not exactly.

Firanka usually means a net curtain or sheer curtain — the thin, often decorative curtain that lets light through. It is different from:

• zasłona = a heavier curtain/drape
• kurtyna = a stage curtain

So Ta firanka jest ładna sounds more like This sheer curtain is nice/pretty than This curtain is nice in the broadest possible sense.

Because firanka is a feminine singular noun, and the demonstrative this has to agree with it.

In Polish:

• ten = masculine
• ta = feminine
• to = neuter

So:

• ta firanka
• ten regał
• to biurko

This agreement is very important in Polish.

For the same reason: ładna has to agree with firanka, which is feminine singular.

Compare:

• firanka jest ładna = the curtain is pretty
• regał jest ładny = the bookcase is pretty
• biurko jest ładne = the desk is pretty

So the adjective changes form depending on the gender of the noun.

In this sentence, jest is needed.

Polish often omits subject pronouns like I, you, he, but the verb to be is normally still used in sentences like this:

• Firanka jest ładna = The curtain is pretty

You generally would not say just Firanka ładna in standard neutral Polish. That can appear in very informal speech, headlines, or special stylistic contexts, but the normal full sentence uses jest.

Because Polish often drops subject pronouns when the verb ending already makes the subject clear.

• chcę = I want
• chcesz = you want
• chce = he/she/it wants

So chcę postawić... already means I want to place/put...

You can add ja for emphasis:

• Ja chcę postawić drugi regał = I want to place a second bookcase

But in a neutral sentence, leaving ja out is more natural.

Because Polish does not use a separate word like English to before the infinitive in this structure.

English:

• I want to put

Polish:

• chcę postawić

The infinitive itself is enough. This is very common after verbs like:

• chcę iść = I want to go
• muszę pracować = I have to work
• lubię czytać = I like to read

Postawić usually means to put, to place, or more literally to set/stand something upright or in position.

With furniture, it is a very natural choice:

• postawić regał
• postawić krzesło
• postawić lampę

Here it means something like place or set the second bookcase somewhere.

It is also a perfective verb, which means it presents the action as a whole or as a completed placement. After chcę, that often sounds natural when you mean a specific intended act: I want to put/place it.

This is a classic Polish aspect pair:

• stawiać = imperfective
• postawić = perfective

Very roughly:

• stawiać focuses on the process, repetition, or general activity
• postawić focuses on one completed act

Examples:

• Chcę postawić regał przy ścianie.
  = I want to place the bookcase by the wall.
  (one concrete act)

• Codziennie stawiam kwiaty na stole.
  = Every day I put flowers on the table.
  (habit/repeated action)

In your sentence, postawić fits because it sounds like one specific intended rearrangement.

Because drugi regał is the direct object of postawić, so it is in the accusative case.

However, for masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

So:

• nominative: drugi regał
• accusative: drugi regał

That is why the form does not change here.

If the noun were masculine animate, you would usually see a different accusative form.

It can mean either, depending on context.

• drugi regał can mean the second bookcase
• It can also mean another bookcase / a second bookcase

In many everyday sentences, Polish drugi is used where English might naturally say another if the idea is one more.

So this sentence could suggest:

• there is already one bookcase, and the speaker wants to place a second one
• or simply another one

The exact nuance depends on the situation.

Because bliżej normally goes with the genitive case.

• biurko = desk (dictionary form, nominative)
• biurka = of the desk / desk in the genitive singular

So:

• bliżej biurka = closer to the desk

This is a very common pattern:

• bliżej domu = closer to home
• bliżej okna = closer to the window
• bliżej ściany = closer to the wall

Yes.

• blisko = close / near
• bliżej = closer

So bliżej is the comparative form.

Examples:

• Biurko jest blisko okna. = The desk is near the window.
• Regał stoi bliżej okna niż biurka. = The bookcase stands closer to the window than to the desk.

In your sentence, bliżej biurka means the speaker wants the bookcase to be in a position closer to the desk than it is now or than some other possible position.

Yes. Polish word order is fairly flexible, though different orders can change emphasis.

The original sentence is neutral and natural:

• Ta firanka jest ładna, ale chcę postawić drugi regał bliżej biurka.

Other possible orders include:

• Ale chcę postawić drugi regał bliżej biurka.
• Drugi regał chcę postawić bliżej biurka.
• Chcę drugi regał postawić bliżej biurka.

These are still understandable, but the original version is a good standard choice for a learner.

They are:

• ta firanka — nominative
  It is the subject of jest.

• drugi regał — accusative
  It is the direct object of postawić.
  It looks the same as nominative because it is masculine inanimate.

• biurka — genitive
  It is used after bliżej.

So this sentence is a good example of how Polish cases can appear together in one short sentence.