Min moster breder gärna smör på kex, men min faster vill hellre ha skinka på sin smörgås.

Swedish distinguishes between maternal and paternal aunts:

• moster = your mother’s sister
• faster = your father’s sister

English usually just says aunt, so this is a detail English speakers often notice right away.

Gärna is a very common Swedish adverb. In this sentence, it means something like:

• gladly
• with pleasure
• or more naturally in English, likes to

So breder gärna smör på kex suggests that she likes spreading butter on crackers or often happily does that.

It does not mean eagerly in a strong emotional sense. It is usually softer and more everyday.

Breder is the present tense of the verb breda, which means to spread.

A few useful forms are:

• infinitive: breda
• present: breder
• past: bredde
• supine: brett

So:

• att breda smör = to spread butter
• hon breder smör = she spreads butter

Swedish present tense often ends in -r, but the exact form depends on the verb.

This is standard Swedish word order. In a main clause, the finite verb usually comes early, and adverbs like gärna often come after it.

So:

• Min moster breder gärna smör på kex

has the pattern:

• subject: Min moster
• verb: breder
• adverb: gärna
• object/rest: smör på kex

This placement is very normal in Swedish.

They refer to different kinds of food:

• kex = cracker or biscuit, depending on context
• smörgås = sandwich or open sandwich

In Swedish, smörgås often suggests a slice of bread with something on top, not necessarily a closed two-slice sandwich in the English sense.

So smör på kex and skinka på sin smörgås sound natural because they involve two different bases for toppings.

Because Swedish uses på (on) with both food combinations here:

• smör på kex = butter on crackers
• skinka på sin smörgås = ham on her sandwich

This works much like English on. Repeating på is completely normal, because each phrase needs its own preposition.

Because smör (butter) and skinka (ham) are being used as general food substances here, not as countable single items.

Swedish often omits articles with mass nouns in this kind of context:

• ha smör på kex
• ha skinka på smörgåsen

This is similar to English, where we also often say butter or ham without a or the.

Vill hellre ha means would rather have or prefers to have.

Breakdown:

• vill = wants
• hellre = rather
• ha = have

So literally it is something like wants rather to have, but natural English is:

• would rather have
• prefers

This is a very common Swedish structure.

That is the normal position for this kind of adverb in a main clause.

In:

• min faster vill hellre ha skinka

the structure is:

• subject: min faster
• finite verb: vill
• adverb: hellre
• infinitive: ha
• object: skinka

So hellre comes after the finite verb vill, which is standard Swedish word order.

Because sin is a reflexive possessive. It is used when the possessor is the same as the subject of the clause.

Here, the subject is min faster, and the sandwich belongs to that same person. So Swedish uses:

• sin smörgås = her own sandwich

If you said hennes smörgås, it would usually suggest that the sandwich belongs to some other female person, not the subject.

This is an important Swedish distinction that English does not usually make.

In Swedish, a possessive like min, din, sin, hennes, and so on usually replaces the article.

So you say:

• min bok = my book
• sin smörgås = her/his own sandwich

You do not normally add the definite ending at the same time in this basic pattern.

Not by itself. Sin does not specifically mean his or her the way English possessives do. It means his/her/their own, depending on the subject.

Examples:

• Han tog sin bok. = He took his own book.
• Hon tog sin bok. = She took her own book.
• De tog sin bok is not standard for plural; with plural subjects Swedish uses sin/sitt/sina according to number and gender of the noun, but for plural possessors the common reflexive possessive is still chosen based on the possessed noun: De tog sina böcker = They took their own books.

In your sentence, sin refers back to min faster.

Because the noun is singular in both cases.

• min = my with a singular common-gender noun
• mina = my with plural nouns

So:

• min moster = my aunt
• min faster = my aunt
• mina mostrar = my aunts
• mina fastrar = my aunts

Both moster and faster are common-gender singular nouns, so min is correct.

Yes. The vocabulary and grammar are natural and standard.

A few points:

• gärna is very common in spoken and written Swedish
• vill hellre ha is a normal way to express preference
• sin is standard and important Swedish grammar
• moster and faster are ordinary family words

The sentence is a good example of natural Swedish, even if the exact situation is a bit specifically descriptive.