Ten sweter jest brudny, bo spadł na mokrą podłogę.

Ten means this and agrees with the noun sweter.

Because sweter is a masculine singular noun, the correct form is ten.

Compare:

• ten sweter = this sweater
• ta koszulka = this T-shirt
• to krzesło = this chair

So you choose ten / ta / to depending on the gender of the noun.

In Polish, nouns have grammatical gender. Sweter is masculine, which you can see from the forms used with it:

• ten sweter
• brudny sweter
• sweter spadł

Those masculine forms all match sweter.

A lot of masculine nouns end in a consonant, and sweter does too, so that is a useful clue.

Adjectives in Polish must agree with the noun in gender, number, and case.

Since sweter is masculine singular, the adjective must also be masculine singular:

• brudny sweter = dirty sweater
• ten sweter jest brudny = this sweater is dirty

Other forms would be used with other noun types:

• brudna podłoga = dirty floor
• brudne okno = dirty window

So brudny matches sweter.

Spadł is the past tense form of spaść = to fall.

It is masculine singular because the thing that fell is sweter, which is masculine.

Compare:

• sweter spadł = the sweater fell
• koszulka spadła = the T-shirt fell
• krzesło spadło = the chair fell

In Polish past tense, the verb often shows the gender of the subject.

Because the sentence describes:

• the sweater’s current state: jest brudny = it is dirty now
• the earlier cause: spadł = it fell earlier

So the meaning is:

• now: the sweater is dirty
• before: it fell onto a wet floor

This mix of tenses is completely natural in both Polish and English.

Because after na in this sentence, the noun is in the accusative case.

The sweater fell onto the floor, so there is movement toward a surface. That requires the accusative:

• na mokrą podłogę = onto a wet floor

The basic dictionary forms are:

• mokra = wet
• podłoga = floor

But in the accusative singular feminine, they change to:

• mokrą
• podłogę

So:

• mokra podłoga = a wet floor
• na mokrą podłogę = onto a wet floor

Here na means onto because there is movement.

A very useful contrast is:

• na + accusative = movement onto/toward a surface
• na + locative = location on a surface

So:

• spadł na mokrą podłogę = it fell onto the wet floor
• leży na mokrej podłodze = it is lying on the wet floor

This is one of the most important uses of na in Polish.

Because the case changes depending on whether you are talking about location or movement.

1. Location: where something is

   • na mokrej podłodze = on the wet floor
     This uses the locative after na.

2. Movement: where something goes

   • na mokrą podłogę = onto the wet floor
     This uses the accusative after na.

So in your sentence, the sweater is moving, which is why you get na mokrą podłogę.

Yes. Both can mean because.

• bo is very common and conversational
• ponieważ is a bit more formal or more careful in style

So both are correct:

• Ten sweter jest brudny, bo spadł na mokrą podłogę.
• Ten sweter jest brudny, ponieważ spadł na mokrą podłogę.

In everyday speech, bo is extremely common.

Not completely. Polish word order is more flexible than English, although some orders sound more natural in normal conversation.

The given sentence is very natural:

• Ten sweter jest brudny, bo spadł na mokrą podłogę.

You could also say:

• Bo spadł na mokrą podłogę, ten sweter jest brudny.

But that sounds more marked or stylistically different. In most ordinary contexts, the original order is the best choice.

Sometimes yes, if the context is clear.

For example, if you are already talking about the sweater, you might say:

• Jest brudny, bo spadł na mokrą podłogę.

Polish often leaves out things that are obvious from context. But in a standalone sentence, keeping ten sweter makes it clear what you mean.

Sweter usually means sweater in general. Depending on the variety of English, it may also overlap with jumper.

So:

• American English: usually sweater
• British English: often jumper

It is a normal everyday word for a knitted upper-body garment.

Yes, spadł can look tricky.

A rough guide:

• sp as in spot
• a like a in father
• dł includes ł, which sounds like English w

So it sounds roughly like spadw, though not exactly.

Two key pronunciation points:

• ł is pronounced like English w
• Polish consonant clusters are often pronounced more tightly than in English

So:

• spadł ≈ spadw

The letter ę is a nasal vowel, but at the end of a word it is often pronounced in a simplified way in everyday speech.

So podłogę may sound roughly like:

• pod-wo-ge or
• pod-wo-geng very lightly, depending on speech style

For a learner, the important things are:

• write it as ę
• recognize it as the accusative ending here
• do not worry if native pronunciation sounds a bit different from careful textbook pronunciation

Also remember:

• ł sounds like w so podłogę begins roughly like pod-wog...

In Polish, clauses introduced by bo are normally separated by a comma.

So:

• Ten sweter jest brudny, bo spadł na mokrą podłogę.

This is standard Polish punctuation. It is similar to English, where a comma before because may sometimes appear depending on structure and style, but in Polish the comma before a subordinate clause like this is much more regular.