Farmor hade på sig en lila jacka, och moster valde en rosa tröja.

They are more specific than the English words grandmother and aunt.

• farmor = father’s mother
• moster = mother’s sister

Swedish often distinguishes family members by which side of the family they are on. For example:

• mormor = mother’s mother
• farmor = father’s mother
• moster = mother’s sister
• faster = father’s sister

So English may simply say grandma and aunt, but Swedish gives you extra information.

In Swedish, close family words are often used without a possessive when it is already clear whose relative is meant.

So farmor can mean something like grandma / my grandmother, and moster can mean aunt / my aunt, depending on context.

You could also say:

• Min farmor hade på sig en lila jacka.
• Min moster valde en rosa tröja.

That is also correct, but the version without min can sound more natural when the relationship is already understood.

Hade på sig means was wearing or had on.

The basic expression is ha på sig, which is a very common Swedish way to talk about clothes.

• ha på sig = to be wearing
• har på sig = is wearing / has on
• hade på sig = was wearing / had on

So:

• Farmor hade på sig en lila jacka = Grandma was wearing a purple jacket

It is an everyday, idiomatic expression.

Because ha på sig is a fixed expression, and sig is the reflexive part of it.

Literally, it is something like have on oneself, though you should think of it as a single unit meaning wear.

The reflexive pronoun changes with the subject:

• Jag hade på mig = I was wearing
• Du hade på dig = you were wearing
• Hon hade på sig = she was wearing
• Vi hade på oss = we were wearing

So in your sentence, sig is used because the subject is third person.

It can move. Both of these are natural:

• Farmor hade på sig en lila jacka.
• Farmor hade en lila jacka på sig.

Both mean the same thing. Swedish often allows this kind of placement with short particles and pronouns. Learners will hear both patterns.

Yes, you could.

• Farmor hade på sig en lila jacka = everyday, very common
• Farmor bar en lila jacka = also correct, but a bit more literary, descriptive, or formal

The verb bära can mean wear in the sense of wearing clothes, but ha på sig is usually the most natural choice in ordinary speech.

Because many colour words like lila and rosa are commonly treated as indeclinable adjectives in Swedish. That means they usually stay the same instead of changing form.

For example:

• en lila jacka
• ett lila hus
• två lila jackor

and:

• en rosa tröja
• ett rosa band
• rosa tröjor

So unlike many other adjectives, these often do not add -t or -a in the usual way.

Because jacka and tröja are en-words in Swedish.

Swedish nouns have grammatical gender, and the indefinite article must match the noun:

• en for common gender nouns
• ett for neuter nouns

So:

• en jacka
• en tröja

The article agrees with the noun, not with the colour word.

Valde is the past tense of välja, which means to choose.

Its main forms are:

• välja = choose
• väljer = chooses / is choosing
• valde = chose
• valt = chosen

So:

• moster valde en rosa tröja = aunt chose a pink sweater

The comma is possible here because it separates two full clauses:

• Farmor hade på sig en lila jacka
• moster valde en rosa tröja

In modern Swedish, a comma before och is often optional in a sentence like this. Many people would also write:

• Farmor hade på sig en lila jacka och moster valde en rosa tröja.

So the comma is mainly a style or readability choice here, not a big grammar issue.

Because Swedish does not normally capitalize common nouns.

Farmor is capitalized only because it is the first word of the sentence. If it appeared later, it would usually be lowercase too.

So:

• Farmor hade på sig... = capitalized because it starts the sentence
• ...och moster valde... = lowercase because it is in the middle of the sentence

This is different from German, for example, where all nouns are capitalized.