Po pracy idziemy do cukierni, bo mam ochotę na pączka.

Pracy is in the locative singular.

The preposition po often takes the locative when it means after. So:

• praca = work
• po pracy = after work

This is a very common pattern:

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

So po pracy is just the normal way to say after work.

Polish often uses the present tense of an imperfective verb to talk about a planned or expected future action, especially when the context already makes the time clear.

So Po pracy idziemy do cukierni sounds like:

• After work, we’re going to the pastry shop
• After work, we’re going to head to the pastry shop

It feels natural and conversational.

You could also say Po pracy pójdziemy do cukierni, which is more explicitly future:

• pójdziemy = we will go

Very roughly:

• idziemy = we’re going / we’re planning to go
• pójdziemy = we will go

After do, Polish uses the genitive.

So:

• cukiernia = pastry shop / confectionery
• do cukierni = to the pastry shop

This is a very common pattern for movement to a place:

• do domu = home / to the house
• do sklepu = to the shop
• do szkoły = to school

So idziemy do cukierni literally means we are going to the pastry shop.

Because do and w mean different things here.

• do cukierni = to the pastry shop
• w cukierni = in the pastry shop

So:

• Idziemy do cukierni = We’re going to the pastry shop.
• Jesteśmy w cukierni = We’re in the pastry shop.

English also makes this distinction, but in Polish it is very important because the preposition changes.

Not exactly.

Cukiernia is more specifically a pastry shop, confectionery, or a shop that sells sweets, cakes, pastries, and things like pączki.

A bread bakery is more often piekarnia.

So:

• piekarnia = bakery, especially for bread
• cukiernia = pastry/confectionery shop

In real life, one place may sell both, but the words are not identical.

Because the subject changes.

The first part is about we:

• idziemy = we are going

The second part gives the reason, and that reason belongs to the speaker only:

• mam ochotę = I feel like / I want

So the sentence means that we are going there because I feel like having a doughnut.

This kind of subject change is very normal in Polish.

Because Polish usually drops subject pronouns when they are clear from the verb ending.

• idziemy already tells you we
• mam already tells you I

So Polish normally says:

• Idziemy rather than My idziemy
• Mam rather than Ja mam

You add my or ja only when you want emphasis or contrast:

• My idziemy do cukierni, a oni do domu.
• Ja mam ochotę na pączka, nie on.

It is a very common Polish expression meaning:

• I feel like
• I’m in the mood for
• I want

Literally, it is something like I have a desire for.

Structure:

• mieć ochotę na + accusative

Examples:

• Mam ochotę na kawę. = I feel like coffee.
• Mam ochotę na pizzę. = I feel like pizza.
• Mam ochotę na spacer. = I feel like a walk.

So mam ochotę na pączka is a standard, natural pattern.

Because ochotę is the accusative singular form, and here it is the direct object of mam.

The basic form is:

• ochota

But after mam:

• mam ochotę

This is a common pattern with many feminine nouns ending in -a:

• kawa → mam kawę
• herbata → mam herbatę
• ochota → mam ochotę

So mam ochotę is just the grammatically correct form of I have a desire / I feel like.

Because after na in this expression, Polish uses the accusative, and pączek commonly has the accusative singular pączka.

So:

• pączek = nominative
• na pączka = accusative after na

This can feel surprising to English speakers, because pączek is not a living thing. But in Polish, some masculine food words often behave this way in the singular accusative.

For example:

• zjeść kotleta
• kupić pączka
• mam ochotę na pączka

So the important thing to learn is the whole pattern:

• mam ochotę na pączka

not mam ochotę na pączek

Yes, bo means because.

In everyday spoken Polish, bo is extremely common and natural.
You could also use ponieważ, but it sounds more formal or written.

So:

• bo = everyday, conversational because
• ponieważ = more formal because / since

In this sentence, bo is the most natural choice.

Because bo introduces a separate clause explaining the reason, and in Polish that is normally preceded by a comma.

So:

• Po pracy idziemy do cukierni, bo mam ochotę na pączka.

This comma is standard Polish punctuation.

You will often see the same with other clauses of explanation or reason.