Po sprzątaniu w domu jest czysto.

Because the preposition po normally requires the locative case when it means after.

The base form is sprzątanie (cleaning / tidying), but after po it changes to the locative singular:

• sprzątanie → nominative
• sprzątaniu → locative

So:

• po sprzątaniu = after cleaning

This is very common in Polish:

• po pracy = after work
• po obiedzie = after lunch
• po filmie = after the film

Not exactly. It is a noun, specifically a verbal noun formed from the verb sprzątać (to clean / tidy up).

So:

• sprzątać = to clean
• sprzątanie = cleaning, the act of cleaning
• po sprzątaniu = after cleaning

Even though it comes from a verb, it behaves grammatically like a noun and can take cases.

Because w meaning in or inside takes the locative case when it refers to location.

The noun is:

• dom = house / home

Its locative singular is:

• domu

So:

• w domu = in the house / at home

This is one of the most common Polish phrases, and you should just memorize it as a set expression.

Because czysto is used in an impersonal expression meaning it is clean or it’s clean.

Compare:

• Dom jest czysty. = The house is clean.

  • czysty is an adjective
  • it agrees with dom

• W domu jest czysto. = It is clean in the house / The house is clean inside.

  • czysto is an adverb-like predicative form
  • it describes the general state of a place

Polish often uses this pattern with places:

• Tu jest cicho. = It’s quiet here.
• W pokoju jest zimno. = It’s cold in the room.
• U was jest przytulnie. = It’s cozy at your place.

There is no explicit subject. This is a very normal impersonal sentence in Polish.

English usually needs a dummy subject:

• It is clean.

Polish does not need that:

• Jest czysto. = It is clean.

So jest czysto is a complete idea by itself, and w domu simply tells you where it is clean.

It can mean either, depending on context.

In this sentence, the most natural interpretation is:

• in the house / in the home
• meaning the home is clean after cleaning

But w domu can also mean at home in other contexts:

• Jestem w domu. = I am at home.

So the phrase is flexible, and context tells you which meaning is intended.

It can mean either.

Without more context, it sounds fairly general:

• After cleaning, the house is clean.

That could describe:

• a usual result
• a general truth
• one specific situation

Polish often leaves that unstated unless the context makes it specific.

Yes, and it is grammatically correct, but the nuance is a little different.

• Po sprzątaniu dom jest czysty.
  = After cleaning, the house is clean.

This focuses on dom as the subject.

• Po sprzątaniu w domu jest czysto.
  = After cleaning, it is clean in the house.

This sounds more like describing the overall condition or atmosphere of the place.

So both are possible, but w domu jest czysto is especially natural when talking about how a place feels or looks generally.

No, Polish word order is fairly flexible.

The original sentence:

• Po sprzątaniu w domu jest czysto.

is natural and emphasizes after cleaning first.

Other possible versions include:

• W domu po sprzątaniu jest czysto.
• Po sprzątaniu jest w domu czysto.

These are all understandable, but they do not sound equally neutral. The original version is a good, natural choice.

In Polish, changing the word order often changes emphasis, not the basic meaning.

In a normal, complete sentence, jest should be there.

• W domu jest czysto. = standard, neutral Polish

If you omit it:

• W domu czysto

that can sound abbreviated, conversational, or like a note, headline, or fragment rather than a full neutral sentence.

So for learners, it is best to keep jest here.

Because Polish has no articles like a or the.

So dom can mean:

• a house
• the house
• house/home

and the exact meaning depends on context.

That is why:

• w domu can mean in the house, in a house, or at home

The listener understands which one is meant from the situation.

Yes, you can.

• po sprzątaniu = after cleaning
• po posprzątaniu = after having cleaned / after the cleaning is finished

The second version is connected with the perfective verb posprzątać, so it can sound a bit more clearly completed.

But po sprzątaniu is very common and natural, and it is probably the safer everyday choice for a learner.