Mój ojciec nosi ciemny krawat, a ja wolę szarą marynarkę bez krawata.

Because ojciec is the subject of the sentence, so it is in the nominative case. The possessive adjective mój has to agree with ojciec in gender, number, and case.

• ojciec = masculine singular nominative
• so: mój ojciec = my father

If the noun changed case, mój would change too. For example:

• Widzę mojego ojca = I see my father
• Pomagam mojemu ojcu = I help my father

So here mój is nominative because ojciec is nominative.

It is the object, but krawat is a masculine inanimate noun, and in Polish the accusative singular of many masculine inanimate nouns looks exactly like the nominative singular.

So:

• nominative: ciemny krawat
• accusative: ciemny krawat

That is why nothing appears to change.

Compare that with a masculine animate noun:

• nominative: dobry pies = a good dog
• accusative: widzę dobrego psa = I see a good dog

So krawat does take accusative after nosi, but the form happens to stay the same.

Because marynarkę is the direct object of wolę (I prefer), so it must be in the accusative case.

The base form is:

• szara marynarka = a grey jacket/blazer
  nominative singular, feminine

But after wolę, you need accusative:

• szarą marynarkę

For feminine singular nouns and adjectives, the accusative often changes like this:

• szara → szarą
• marynarka → marynarkę

So:

• wolę szarą marynarkę = I prefer a grey jacket/blazer

Because the preposition bez (without) always requires the genitive case.

So:

• nominative: krawat
• genitive: krawata

That gives:

• bez krawata = without a tie

This is a very important pattern in Polish: many prepositions require a specific case, and bez always goes with the genitive.

Other examples:

• bez cukru = without sugar
• bez mleka = without milk
• bez samochodu = without a car

In this sentence, a links two contrasting ideas:

• Mój ojciec nosi ciemny krawat, a ja wolę szarą marynarkę bez krawata.

It means something like:

• and, but with a contrast
• sometimes close to while
• sometimes close to whereas

So the sense is:

• My father wears a dark tie, whereas I prefer a grey jacket without a tie.

Why not the others?

• i = simple and, just adding information
• ale = but, often stronger contradiction

Here a is natural because the speaker is calmly contrasting two preferences/styles, not making a strong objection.

Yes, Polish can often omit subject pronouns, because the verb ending already shows the person.

• wolę already means I prefer

So you could say:

• Mój ojciec nosi ciemny krawat, a wolę szarą marynarkę bez krawata.

But including ja is very natural here because it emphasizes the contrast:

• my father ... and I ...
• he does one thing, I prefer another

So ja is not required for grammar, but it helps express contrast clearly.

Not exactly. Nosić usually means to wear in the sense of having something on regularly, habitually, or as part of one’s style.

So:

• Mój ojciec nosi ciemny krawat = My father wears a dark tie

It does not usually mean the moment of putting it on. For that, Polish often uses a different verb, such as:

• zakładać / założyć = to put on

So the difference is roughly:

• nosić = wear
• założyć = put on

It is the 1st person singular present tense of woleć (to prefer):

• (ja) wolę = I prefer
• (ty) wolisz = you prefer
• on/ona woli = he/she prefers
• my wolimy = we prefer
• wy wolicie = you prefer
• oni/one wolą = they prefer

It is a common verb and its forms are worth memorizing. The stem changes a little, so for learners it can feel irregular, but it is just the normal conjugation of woleć.

Yes, sometimes possessive words like mój are omitted in Polish if the meaning is obvious from context.

For example, in the right situation, ojciec might already clearly mean my father.

However, mój ojciec is perfectly natural and often clearer, especially when introducing the person or making a comparison:

• Mój ojciec ... a ja ...

That structure makes the contrast very clear: my father versus I.

So mój is not always strictly necessary, but it is very natural here.

Polish word order is more flexible than English, because case endings show grammatical roles. The neutral order here is very natural:

• Mój ojciec nosi ciemny krawat, a ja wolę szarą marynarkę bez krawata.

But some rearrangement is possible for emphasis. For example:

• Ja wolę szarą marynarkę bez krawata, a mój ojciec nosi ciemny krawat.

This changes the focus slightly, but the meaning stays basically the same.

Still, not every order sounds equally natural in every context. For learners, the original order is a good standard model.

It can mean either, depending on context, but very often marynarka refers to a blazer or a suit-style jacket, not just any jacket.

So in this sentence:

• szara marynarka most likely means a grey blazer / suit jacket

If you wanted a more general everyday outer jacket, Polish often uses kurtka instead.

So:

• marynarka = blazer, suit jacket
• kurtka = jacket/coat-type outerwear

In Polish, adjectives must agree with nouns in gender, number, and case.

Here are the two adjective-noun pairs:

• ciemny krawat
• szarą marynarkę

Why the different endings?

1. ciemny krawat

   • krawat is masculine singular
   • here it is accusative, but masculine inanimate accusative looks like nominative
   • so the adjective stays ciemny

2. szarą marynarkę

   • marynarka is feminine singular
   • it is in the accusative
   • so:
   • szara → szarą
   • marynarka → marynarkę

This agreement system is one of the key features of Polish grammar.