Jeśli mam w domu mąkę i maliny, mogę upiec proste ciasto na weekend.

Yes. Jeśli means if and introduces a condition.

In this sentence, Jeśli mam w domu mąkę i maliny... means If I have flour and raspberries at home...

You may also see jeżeli, which also means if. In most everyday contexts, jeśli and jeżeli are interchangeable, though jeżeli can sound a little more formal or careful.

Because mam refers to the condition now: if I have flour and raspberries at home.

The speaker is talking about a present situation that makes something possible. Polish often uses the present tense in this kind of if sentence, just as English does:

• If I have time, I can do it tomorrow.
• Jeśli mam czas, mogę to zrobić jutro.

So the weekend is in the future, but the condition is about what the speaker has at the moment.

Because the preposition w meaning in usually requires the locative case when it describes location.

So:

• dom = house/home
• w domu = in the house / at home

This is why the noun changes form. After w in a location sense, you often need the locative:

• w szkole = at school
• w pracy = at work
• w domu = at home

Because mąkę is the accusative singular form of mąka.

The verb mam means I have, and what follows is a direct object, so Polish uses the accusative case:

• nominative: mąka = flour
• accusative: mąkę = flour (as the object)

This is very common with feminine nouns ending in -a:

• książka → książkę
• kawa → kawę
• mąka → mąkę

Here maliny is the accusative plural, but for non-masculine-personal nouns, the accusative plural is often the same as the nominative plural.

So:

• nominative plural: maliny = raspberries
• accusative plural: maliny = raspberries

You would use malin in other contexts, for example the genitive plural:

• Nie mam malin = I don't have any raspberries

That contrast is useful:

• Mam maliny = I have raspberries
• Nie mam malin = I don't have raspberries

This is about aspect, which is very important in Polish verbs.

• piec = imperfective, focusing on the process of baking
• upiec = perfective, focusing on baking something successfully/to completion

In this sentence, mogę upiec proste ciasto means I can bake a simple cake as a complete result.

If you said mogę piec, it would sound more like I can be baking / I am able to bake / I can bake in general, with more focus on the activity rather than a finished cake.

So here upiec is natural because the idea is: I can make a cake.

Yes, the prefix is important. In many Polish verbs, prefixes help create a perfective verb.

Here:

• piec = to bake
• upiec = to bake completely / to bake successfully

The prefix does not always translate directly into a separate English word, but it changes how the action is viewed.

Compare:

• Będę piec ciasto. = I’ll be baking a cake.
• Upiekę ciasto. = I’ll bake a cake. / I’ll have a cake baked.

So in your sentence, mogę upiec sounds natural because the speaker means a completed result.

Because ciasto is a neuter singular noun, and the adjective has to agree with it in gender, number, and case.

So:

• prosty = simple (basic dictionary form, masculine)
• proste = simple (neuter singular)
• ciasto = cake, dough (neuter singular)

Since ciasto here is neuter singular, the adjective must also be neuter singular:

• proste ciasto

Also, because ciasto is an inanimate noun, its accusative singular is the same as its nominative singular, so nothing changes visibly here.

It can mean cake, cake/pastry, or dough, depending on context.

In this sentence, upiec proste ciasto clearly means bake a simple cake.

But in other contexts:

• ciasto na pizzę = pizza dough
• ciasto czekoladowe = chocolate cake
• robić ciasto can sometimes mean make dough or make a cake mixture, depending on context

So ciasto is a broad word, and context tells you which meaning is intended.

Here na weekend means something like for the weekend.

The preposition na often has several meanings, and one common use is for / intended for / for a particular occasion or time.

So:

• ciasto na weekend = a cake for the weekend
• coś na obiad = something for lunch
• prezent na urodziny = a present for a birthday

In this sentence, the idea is that the cake is intended to be made or eaten over the weekend.

Because weekend is a normal, widely used word in Polish. It is a borrowing from English, but it behaves like a regular Polish noun.

You will hear and see it very often:

• na weekend = for the weekend
• w weekend or w weekendy = at the weekend / on weekends

There is no more common native everyday alternative that would replace it in ordinary speech.

Because Jeśli mam w domu mąkę i maliny is a subordinate clause introduced by jeśli, and in Polish such clauses are normally separated by a comma.

So the structure is:

• Jeśli mam w domu mąkę i maliny, = If I have flour and raspberries at home,
• mogę upiec proste ciasto na weekend. = I can bake a simple cake for the weekend.

This comma is standard Polish punctuation.

Yes. Polish word order is more flexible than English word order, though not completely free.

For example, you could also say:

• Mogę upiec proste ciasto na weekend, jeśli mam w domu mąkę i maliny.

This means essentially the same thing.

The original version puts the condition first, which is very natural because it sets up the situation before giving the result.

Word order in Polish often changes emphasis rather than the basic meaning.

Yes, you could say:

• Jeżeli mam w domu mąkę i maliny, mogę upiec proste ciasto na weekend.

The meaning stays basically the same.

If there is any difference, it is mostly stylistic:

• jeśli = very common, neutral, everyday
• jeżeli = also common, sometimes a bit more formal or deliberate

For a learner, both are good to know, but jeśli is probably the one you will hear most often in casual speech.

Often yes, but not always in exactly the same way as English can.

Here mogę means I can / I am able to / it is possible for me to.

Depending on context, móc can express:

• ability
• possibility
• permission
• practical opportunity

In this sentence, it is mostly practical possibility: if I have the ingredients, then making the cake is possible.

So mogę is a good translation of I can, but it is useful to remember that its meaning depends on context.

It is accusative after the preposition na.

The noun weekend is masculine inanimate, and in the accusative singular it looks the same as the nominative:

• nominative: weekend
• accusative: weekend

So there is no visible change here, but grammatically it is still accusative because na in this meaning requires it.

It sounds like a general but realistic possibility: if I have those ingredients, I can bake a simple cake for the weekend.

Polish has no articles, so proste ciasto can mean:

• a simple cake
• sometimes the simple cake, depending on context

Here, English would most naturally use a simple cake.

That is one of the things English speakers need to get used to in Polish: nouns often appear without anything corresponding to a or the, and context does the work instead.