Innbruddet skjedde i går.

Because Norwegian usually puts the definite article on the end of the noun.

• et innbrudd = a burglary / a break-in
• innbruddet = the burglary / the break-in

The ending -et is the definite singular ending for many neuter nouns. So this sentence is talking about the burglary, not just a burglary.

Yes, but the meaning and context change a little.

• Innbruddet skjedde i går suggests a specific burglary that is already known from the context.
• Et innbrudd skjedde i går is grammatically possible, but it sounds less natural in many situations.
• More natural ways to introduce new information would often be:
  • Det skjedde et innbrudd i går
  • Det var et innbrudd i går

So innbruddet works best when the burglary is already identified in some way.

Skjedde is the past tense of skje, which means to happen or to take place.

Useful forms:

• å skje = to happen
• skjer = happens / is happening
• skjedde = happened
• har skjedd = has happened

So in this sentence, skjedde tells you the event happened in the past.

Yes. Its forms are not built in a fully regular way, so it is best to learn them as a set:

• å skje
• skjer
• skjedde
• har skjedd

A learner often expects something more predictable, but skje is one of those common verbs you simply memorize.

Because i går refers to a finished time in the past: yesterday.

In Norwegian, when the time is clearly finished, the simple past is normally used:

• Innbruddet skjedde i går

Using the present perfect with i går would normally be wrong:

• har skjedd i går ❌

This is similar to English, where It happened yesterday is natural, but It has happened yesterday is not.

It is simply a fixed expression that means yesterday. You should learn it as a whole phrase.

Related time expressions are:

• i dag = today
• i morgen = tomorrow
• i går = yesterday

The i here is part of the expression. It does not translate neatly word-for-word in a way that helps much, so the best approach is to memorize i går as one unit.

Yes:

• I går skjedde innbruddet.

That is correct Norwegian.

But when you move i går to the front, Norwegian still keeps the verb in the second position. This is the famous V2 word order rule.

So:

• Innbruddet skjedde i går ✅
• I går skjedde innbruddet ✅
• I går innbruddet skjedde ❌

That last version sounds wrong in standard Norwegian.

Usually, yes, in a sentence like this. Skje is a normal verb for events:

• Hva skjedde? = What happened?
• Ulykken skjedde i natt = The accident happened last night

In some contexts, English might also use take place, and Norwegian skje can cover that idea too. In this sentence, skje is a very natural choice.

A rough learner-friendly approximation is:

INN-brood-deh SHED-deh ee GOR

A few notes:

• innbruddet
  • stress on the first syllable
  • the u sound is not exactly like English oo, but brood is a useful rough guide
• skjedde
  • skj is pronounced more like sh than English sk
  • so it sounds roughly like SHED-deh
• i går
  • i sounds like ee
  • går has a long vowel, roughly gor

Pronunciation varies by dialect, but this approximation is good enough to get started.