Po pracy chcę zacząć czytać nową powieść.

Because the preposition po in the sense of after requires the locative case.

• praca = work
• po pracy = after work

So praca changes to pracy because of the preposition po.

This is a very common pattern:

• po szkole = after school
• po obiedzie = after lunch
• po filmie = after the film

Usually po pracy is an idiomatic everyday phrase meaning after work / after my workday.

It normally does not sound like after the work in the sense of finishing a particular task. It usually refers to the general time after someone is done with work for the day.

So learners should think of po pracy as a fixed, natural expression.

Because Polish often leaves out subject pronouns when they are clear from the verb ending.

Here, chcę means I want, so ja is unnecessary.

• (Ja) chcę = I want

Adding ja is possible, but it usually adds emphasis:

• Ja chcę zacząć czytać... = I want to start reading...

Without emphasis, Polish normally just says chcę.

This is a normal Polish verb chain.

The structure is:

• chcę = I want
• zacząć = to start / to begin
• czytać = to read

So the logic is:

I want + to start + to read

In other words, chcę takes an infinitive, and that infinitive (zacząć) itself takes another infinitive (czytać).

This kind of stacking is completely normal in Polish, just like in English:

• I want to start reading
• Chcę zacząć czytać

Because zacząć is the perfective verb, and here it fits the idea of starting at a particular moment.

• zacząć = to start, to begin (as a completed starting event)
• zaczynać = to be starting / to start habitually or repeatedly

In this sentence, the speaker means a single future plan: after work, they want to begin reading. That is why zacząć sounds natural.

Using zaczynać here would usually sound less natural unless you meant something habitual or repeated.

Because after zacząć Polish normally uses the imperfective verb for the activity that is beginning.

• zacząć czytać = to start reading
• czytać is imperfective, so it describes the activity itself

By contrast:

• przeczytać means to read through / finish reading

So zacząć przeczytać is not the normal way to say start reading. Polish prefers zacząć czytać.

A useful rule: After verbs like zacząć (to start) and przestać (to stop), Polish usually uses the imperfective infinitive.

Because powieść is the direct object of czytać, so it goes into the accusative case.

• nowa powieść = a new novel / the new novel (nominative)
• czytać nową powieść = to read a new novel / the new novel (accusative)

The adjective changes:

• nowa → nową

The noun powieść happens to look the same in the nominative and accusative singular:

• nominative: powieść
• accusative: powieść

So only the adjective clearly shows the accusative here.

Because Polish has no articles.

So nową powieść can mean:

• a new novel
• the new novel

Context tells you which one is meant.

In an isolated sentence like this, English speakers often understand it as a new novel, but grammatically Polish itself does not mark that difference with articles.

Yes. Polish word order is more flexible than English word order.

The sentence:

Po pracy chcę zacząć czytać nową powieść.

is natural because it starts with the time expression po pracy.

But you could also say:

• Chcę po pracy zacząć czytać nową powieść.
• Nową powieść chcę zacząć czytać po pracy.

These versions are grammatically possible, but they shift the emphasis.

The original sentence is a very natural neutral choice if you want to begin with after work.

Not exactly.

• książka = book
• powieść = novel

So powieść is more specific. It refers to a work of fiction of novel length, not just any book.

That means the sentence is specifically about starting to read a new novel, not just a new book.