Jeśli w lodziarni będzie duża kolejka, kupimy po drożdżówce i pójdziemy do parku.

This is a very common question because Polish and English work differently here.

In Polish, after jeśli (if), you can normally use the future tense when you are talking about a real future possibility:

• Jeśli w lodziarni będzie duża kolejka...
• literally: If there will be a big line at the ice cream shop...

That is completely natural in Polish.

In English, by contrast, standard usage is:

• If there is a long line...

So this is one of those places where you should not translate the tense directly from English.

A good rule:

• English: after if, often use present for future meaning
• Polish: after jeśli, very often use the future

Lodziarni is in the locative case.

The preposition w can mean in or at, and when it expresses location, it takes the locative:

• lodziarnia = ice cream shop / ice cream parlor
• w lodziarni = in / at the ice cream shop

So the pattern is:

• nominative: lodziarnia
• locative: w lodziarni

This is the same kind of pattern as:

• w domu = in the house
• w szkole = at school
• w kawiarni = in the café

Because duża kolejka is the subject of the clause, so it stays in the nominative case.

In:

• będzie duża kolejka

the thing that will exist / will be there is duża kolejka (a big line / a long queue).

So:

• duża agrees with kolejka
• both are in the nominative singular feminine

Forms:

• duży = masculine
• duża = feminine
• duże = neuter

Since kolejka is feminine, the adjective must be duża.

Here, kolejka means a line or a queue of people waiting.

So:

• duża kolejka = a big line / a long queue

For a native English speaker, line is often the most natural translation in American English, while queue is common in British English.

Be aware that kolejka can also have other meanings in different contexts, for example:

• a small railway
• a little train
• a shot of alcohol in some informal contexts

But in this sentence, because we are talking about an ice cream shop, it clearly means a line of customers.

Here po means something like one each.

So:

• kupimy po drożdżówce = we’ll buy a sweet yeast bun each

This is a very useful Polish structure:

• po + locative singular for singular countable nouns
• it expresses distribution: one per person

Examples:

• Dostaliśmy po cukierku. = We each got a candy.
• Kupili po bilecie. = They each bought a ticket.
• Weźmy po kawie. = Let’s each have a coffee.

In your sentence, the idea is not just we’ll buy a yeast bun, but specifically each of us will buy one.

Because after po in this distributive meaning, Polish uses the locative case.

Base form:

• drożdżówka = a sweet yeast bun / sweet roll / Danish-like pastry

After po:

• po drożdżówce

So the form changes from nominative drożdżówka to locative drożdżówce.

This is similar to:

• kawa → po kawie
• herbata → po herbacie
• kanapka → po kanapce

So the ending -e here is a normal locative ending for many feminine nouns.

The difference is important:

• kupimy drożdżówkę = we’ll buy a sweet bun
• kupimy po drożdżówce = we’ll buy one sweet bun each

Without po, the sentence simply says that a sweet bun will be bought, but it does not clearly express distribution between the people involved.

With po, the meaning is specifically:

• each person gets one

So if two people are speaking, kupimy po drożdżówce strongly suggests:

• one for me
• one for you

Because kupić and pójść are perfective verbs, and here Polish is talking about single completed future actions.

• kupimy = we will buy
• pójdziemy = we will go / we will set off and go

Perfective verbs in Polish form the future without będę / będziemy.

So:

• kupić → kupimy
• pójść → pójdziemy

This is the normal way to express:

• one completed act of buying
• one act of going somewhere

By contrast, będziemy kupować would suggest a more ongoing, repeated, or process-like action:

• we will be buying

And będziemy iść is generally not how Polish normally says we will go in this situation. For a single motion toward a destination, pójdziemy is the natural choice.

Yes. I simply means and.

So:

• kupimy po drożdżówce i pójdziemy do parku
• we’ll buy a sweet bun each and go to the park

This is a normal coordination of two actions with the same subject:

• we will buy
• we will go

Polish does this very naturally, just like English.

Because the sentence starts with a subordinate clause:

• Jeśli w lodziarni będzie duża kolejka = If there is / will be a long line at the ice cream shop

Then comes the main clause:

• kupimy po drożdżówce i pójdziemy do parku

In Polish, a clause introduced by jeśli is normally separated by a comma from the main clause.

So the comma here is standard and required:

• Jeśli ..., kupimy ...

This is similar to English punctuation in:

• If it rains, we’ll stay home.

Yes, Polish word order is fairly flexible, although some versions sound more natural than others.

The original sentence is very natural:

• Jeśli w lodziarni będzie duża kolejka, kupimy po drożdżówce i pójdziemy do parku.

You could also say:

• Kupimy po drożdżówce i pójdziemy do parku, jeśli w lodziarni będzie duża kolejka.

That means the same thing:

• We’ll buy a sweet bun each and go to the park if there’s a long line at the ice cream shop.

Polish word order changes are often used for:

• emphasis
• rhythm
• information structure

But for a learner, the original order is a very good neutral model.

No, but it is the most straightforward and common choice.

You could also encounter gdy in some contexts, especially when English might use if/when:

• Gdy będzie duża kolejka...

However, jeśli is the clearest standard word for a condition:

• if

It is a good default choice for learners.

Do not confuse this with more hypothetical or unreal structures such as:

• gdyby = if ... were / if ... would

For example:

• Gdyby była duża kolejka, kupilibyśmy po drożdżówce.
• If there were a long line, we would buy a sweet bun each.

That is a different type of condition from your sentence.

Because do expresses movement to a place, and it takes the genitive case.

Base form:

• park = park

After do:

• do parku = to the park

So this is a standard movement pattern:

• iść do domu = go home
• jechać do miasta = go to the city
• pójść do sklepu = go to the shop
• pójdziemy do parku = we’ll go to the park

This contrasts with location:

• w parku = in the park

So:

• do parku = destination
• w parku = location