Regjeringen endrer planen.

Because Norwegian usually puts the definite article at the end of the noun instead of using a separate word before it.

• regjering = government
• regjeringen = the government
• plan = plan
• planen = the plan

So both nouns here are in the definite form.

The base forms are:

• regjering = government
• å endre = to change
• plan = plan

In the sentence:

• Regjeringen is the definite form of regjering
• endrer is the present tense of å endre
• planen is the definite form of plan

endrer is the present tense of å endre.

So it can mean:

• changes
• is changing

Norwegian present tense often covers both the English simple present and present progressive, depending on context.

Yes. å endre is a regular verb in Bokmål.

A basic pattern is:

• infinitive: å endre
• present: endrer
• past: endret
• past participle: endret

So endrer follows a very common pattern.

No. Norwegian verbs do not change for person or number in the present tense.

You say:

• jeg endrer = I change / am changing
• du endrer = you change / are changing
• regjeringen endrer = the government changes / is changing
• de endrer = they change / are changing

So unlike English, there is no special -s form for he/she/it.

That is a very common learner question.

In Bokmål, many nouns that are historically feminine can often take either:

• a feminine definite ending: -a
• a masculine/common definite ending: -en

So you may see both:

• regjeringen
• regjeringa

Both can be correct in Bokmål, depending on style. regjeringen is very common and neutral in formal written Bokmål.

It uses the normal subject–verb–object order:

• Regjeringen = subject
• endrer = verb
• planen = object

So literally:

• subject: the government
• verb: changes / is changing
• object: the plan

This is the basic word order in many simple Norwegian statements.

It is singular.

• regjering = a government
• regjeringen = the government
• regjeringer = governments
• regjeringene = the governments

So the sentence talks about one government.

Yes.

Norwegian present tense often does the work of both English forms:

• The government changes the plan
• The government is changing the plan

Usually the context tells you which meaning is intended.

You usually put ikke after the verb:

• Regjeringen endrer ikke planen.

That means The government does not change the plan or is not changing the plan.

So the pattern is often:

• subject + verb + ikke
  • object

In a yes/no question, Norwegian usually puts the verb first:

• Endrer regjeringen planen?

That means Is the government changing the plan? or Does the government change the plan?

So the statement:

• Regjeringen endrer planen.

becomes the question:

• Endrer regjeringen planen?

Because the sentence is talking about specific things:

• the government
• the plan

If you wanted indefinite nouns instead, you would use something like:

• En regjering endrer en plan.

But that would sound much more general: A government changes a plan. The original sentence refers to particular, known things.