I dag kjøpte jeg mais og bønner fordi vi skal spise restemat i morgen.

This is because Norwegian main clauses follow the V2 rule: the finite verb must come in second position.

• I dag = first element
• kjøpte = second element
• jeg = comes after the verb

So:

• I dag kjøpte jeg mais og bønner
• Jeg kjøpte mais og bønner i dag

Both are correct, but the emphasis is a little different:

• I dag kjøpte jeg ... highlights today
• Jeg kjøpte ... i dag is more neutral

This word order is one of the most important differences between English and Norwegian.

Kjøpte is the past tense of å kjøpe = to buy.

Basic forms:

• å kjøpe = to buy
• kjøper = buy / am buying / buys
• kjøpte = bought
• har kjøpt = have bought

So in this sentence, kjøpte tells you the buying happened in the past: earlier today.

Norwegian often leaves out articles in exactly these kinds of cases.

• mais is usually treated like a mass noun here, similar to corn in English
• bønner is indefinite plural, and indefinite plural normally has no article in Norwegian

So:

• mais = corn
• bønner = beans

Compare:

• en bønne = a bean
• bønner = beans
• bønnene = the beans

And:

• maisen would mean the corn, if you were talking about a specific corn item or batch

Because Norwegian makes compound nouns very freely, and they are usually written as one word.

Here:

• rest = remainder / leftover
• mat = food

So restemat literally means leftover food.

This is very typical in Norwegian. English often uses two words where Norwegian uses one:

• restemat = leftover food
• sommerferie = summer vacation
• barneskole = primary school

A good habit for learners is to expect Norwegian compounds to be written together.

Here skal expresses a future plan or something that is expected to happen.

So vi skal spise restemat i morgen means something like:

• we’re going to eat leftovers tomorrow
• we’ll be eating leftovers tomorrow

In other contexts, skal can also mean something closer to:

• shall
• must
• be supposed to

So its exact meaning depends on context. In this sentence, it sounds like a plan or arrangement, not a strong obligation.

Because fordi starts a subordinate clause, and subordinate clauses do not use the normal main-clause V2 pattern.

Main clause:

• I dag kjøpte jeg ...

Subordinate clause after fordi:

• fordi vi skal spise restemat i morgen

In subordinate clauses, the usual order is:

• subject + verb

So:

• fordi vi skal spise ... = correct
• fordi skal vi spise ... = incorrect

This is another very important Norwegian pattern:

• Main clause: V2
• Subordinate clause: more regular subject-verb order

Yes, they are very common fixed time expressions.

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

You should learn them as whole phrases.

A useful detail: in normal writing, dag, morgen, and går are not capitalized. The sentence only begins with I because it is the first word of the sentence.

So:

• I dag kjøpte jeg ... but inside a sentence:
• Jeg kjøpte mais i dag

Often yes. Norwegian allows some flexibility with adverbials like time expressions.

For example, you can say:

• I dag kjøpte jeg mais og bønner fordi vi skal spise restemat i morgen.
• Jeg kjøpte mais og bønner i dag fordi vi skal spise restemat i morgen.

Both are natural.

You can also sometimes move i morgen, but the sentence may sound a little different depending on what you want to emphasize.

In general:

• earlier position = more emphasis
• later position = often more neutral

So word order is flexible, but not random. The V2 rule and subordinate clause word order still have to be respected.

Yes. The subject changes because the two clauses are talking about different things.

• jeg kjøpte = I bought
• vi skal spise = we are going to eat

So the speaker is the one who bought the food, but the plan for tomorrow includes a group, not just the speaker.

This is very natural in Norwegian, just as in English. It is a good reminder that each clause has its own subject:

• main clause subject: jeg
• subordinate clause subject: vi