Jag ringde nyss min syster.

Ringde is the preterite (simple past) of ringa, which means to call / to phone.

Useful forms:

• infinitive: ringa
• present: ringer
• preterite: ringde
• supine: ringt

So Jag ringde ... is a completed past action: I called ...

Nyss means just, a moment ago, or recently.

It tells you that the phone call happened very shortly before the speaker is speaking. It is a very common word for recent past time.

Compare:

• Jag ringde nyss min syster. = I just called my sister.
• Jag ringde min syster igår. = I called my sister yesterday.

Swedish possessives change form depending on the noun.

• min = for a singular common-gender noun
• mitt = for a singular neuter noun
• mina = for a plural noun

Syster is a singular common-gender noun, so you say min syster.

Examples:

• min syster = my sister
• mitt hus = my house
• mina systrar = my sisters

After a possessive like min, Swedish normally uses the noun without the definite ending.

So:

• min syster = my sister
• not min systern

This is a very important pattern in Swedish:

• min bok = my book
• hans bil = his car
• våra vänner = our friends

English learners often expect something like my the sister, but Swedish does not work that way.

Because ringa often takes a direct object in Swedish.

So:

• ringa någon = call someone

That means min syster directly follows the verb as the object.

Examples:

• Jag ringde min syster.
• Hon ringde sin vän.

Some speakers also use ringa till någon, but for a learner, ringa någon is the safest basic pattern to learn first.

In a normal Swedish main clause, the finite verb usually comes early, and short adverbs like nyss often come right after it.

So this order is very natural:

• Jag ringde nyss min syster.

Structure:

• Jag = subject
• ringde = finite verb
• nyss = adverb
• min syster = object

You can also say:

• Jag ringde min syster nyss.

Both are possible. The version with nyss right after the verb is especially common and natural.

Yes. That is also correct.

Difference:

• Jag ringde nyss min syster = simple past / preterite
• Jag har nyss ringt min syster = present perfect

Both can be used for a very recent action. In modern spoken Swedish, the preterite is often used quite freely, even for something that happened just a moment ago. The present perfect can feel a bit more connected to the present moment or the current situation.

So both are good, but they are not always identical in tone.

A rough learner-friendly pronunciation is:

yah RING-deh nüss min SIS-ter

A few notes:

• Jag is often pronounced a bit like yah in everyday speech.
• ringde has two clear parts: ring-de
• nyss and syster contain the Swedish y sound, which does not exist in normal English. It is similar to German ü or French u.
• syster is stressed on the first syllable: SYS-ter

If you want to sound natural, the hardest part is usually the vowel in nyss and syster.

It can mean both, depending on context.

Originally, ringa is connected with ringing, like making something ring. But in everyday modern Swedish, ringa very often means to call / to phone.

So in this sentence, ringde is naturally understood as called/phoned, not as rang in the bell sense. Context makes that clear.