Mój szary sweter leży na krześle, a twoja czarna bluza wisi na wieszaku.

Because Polish possessive words like mój (my) and twój / twoja (your) have to agree with the noun they describe.

Here:

• sweter is masculine singular, so you get mój sweter
• bluza is feminine singular, so you get twoja bluza

In English, my and your do not change. In Polish, they do.

For example:

• mój sweter
• moja bluza
• moje krzesło

So the form depends on the gender, number, and case of the noun.

For the same reason: adjectives in Polish must agree with the noun.

Here:

• sweter is masculine singular, so szary
• bluza is feminine singular, so czarna

So Polish matches the adjective to the noun:

• szary sweter = masculine
• czarna bluza = feminine

If the noun changed, the adjective would change too:

• czarne krzesło = neuter
• szare swetry = plural

The nouns are:

• sweter — masculine
• bluza — feminine
• krzesło — neuter
• wieszak — masculine

This matters because Polish uses gender for agreement with adjectives, possessives, and sometimes verb forms in the past tense.

A useful beginner pattern is:

• many nouns ending in a consonant are masculine
• many nouns ending in -a are feminine
• many nouns ending in -o or -e are neuter

These are helpful rules, though not perfect in every case.

Because they are the subjects of the two clauses, so they are in the nominative case.

In this sentence:

• Mój szary sweter leży...
• twoja czarna bluza wisi...

The sweater and the hoodie/sweatshirt are the things doing the action, so Polish uses the nominative.

That is why you see:

• sweter, not some changed form
• bluza, not some changed form

Polish often prefers specific position verbs where English might just say is.

Here:

• leży means is lying / lies
• wisi means is hanging / hangs

So:

• a sweater on a chair is naturally described as leży
• a hoodie/sweatshirt on a hanger is naturally described as wisi

You could sometimes say jest na krześle or jest na wieszaku, and it would be understandable, but it is less vivid and less natural in this kind of everyday description.

They are 3rd person singular present tense forms.

That is because the subjects are singular nouns:

• sweter leży
• bluza wisi

In English, you might think of this as it lies and it hangs.

The dictionary forms are:

• leżeć = to lie
• wisieć = to hang

So:

• leży = he/she/it lies, is lying
• wisi = he/she/it hangs, is hanging

Because after na when it means location (on in the sense of where?), Polish uses the locative case.

Here the sentence tells you where the items are:

• on the chair
• on the hanger

So you get:

• na krześle
• na wieszaku

A very important contrast is:

• where? → na
  • locative
• onto what? / to where? → na
  • accusative

Compare:

• Sweter leży na krześle. = The sweater is on the chair.
• Kładę sweter na krzesło. = I put the sweater onto the chair.

Because nouns usually change their endings in different cases.

The basic forms are:

• krzesło
• wieszak

But after na for location, they must be in the locative:

• na krześle
• na wieszaku

wieszak → wieszaku is fairly straightforward.

krzesło → krześle is a form you simply need to learn. Some nouns change not only the ending, but also the stem slightly when declined.

So the important thing to remember is:

• dictionary form: krzesło
• after na for location: na krześle

Here a works a lot like and, but with a slight sense of contrast or comparison.

So in this sentence it connects two parallel ideas:

• my grey sweater is on the chair
• your black hoodie/sweatshirt is on the hanger

Using a feels natural because the sentence is comparing two things:

• my sweater vs your hoodie/sweatshirt
• on the chair vs on the hanger

Polish also has i, which often means a simple and. But a is very common when two parts are being set side by side.

Because in Polish, when a joins two clauses, you normally put a comma before it.

So:

• Mój szary sweter leży na krześle, a twoja czarna bluza wisi na wieszaku.

This is standard Polish punctuation.

It is similar to English when two full clauses are linked, though Polish is often more regular about using the comma here.

Yes. Polish word order is more flexible than English word order because case endings show the grammatical roles.

The version you have is very natural and clear:

• Mój szary sweter leży na krześle, a twoja czarna bluza wisi na wieszaku.

But you could also say:

• Na krześle leży mój szary sweter, a na wieszaku wisi twoja czarna bluza.

That version puts more focus on the locations first.

So the meaning stays basically the same, but the emphasis changes.

Not always. Bluza is a broader word and can mean something like sweatshirt, hoodie, or similar casual top, depending on context.

If you want to be very specific about hoodie, Polish often says:

• bluza z kapturem = hoodie

So in many learning materials, bluza may be translated as hoodie, but in real use it can be wider than that.

Polish stress is usually on the second-to-last syllable of a word.

So for these words:

• szary → stress on SZA
• sweter → stress on SWE
• leży → stress on LE
• krześle → stress on KRZEŚ
• twoja → stress on TWO
• czarna → stress on CZAR
• bluza → stress on BLU
• wisi → stress on WI
• wieszaku → stress on SZA

A rough pronunciation guide:

• mój ≈ mooy
• szary ≈ SHA-ri
• sweter ≈ SVE-ter
• leży ≈ LE-zhih
• krześle ≈ KSHESH-leh
• twoja ≈ TVO-ya
• czarna ≈ CHAR-na
• bluza ≈ BLOO-za
• wisi ≈ VEE-shi
• wieszaku ≈ vye-SHA-koo

The exact sounds are not the same as English sounds, but this approximation can help at first.