Prøveperioden begynner i dag.

Because Norwegian often puts the definite article at the end of the noun instead of using a separate word like the.

• prøveperiode = trial period / probation period
• prøveperioden = the trial period

So the ending -en here means the.

This is very common in Norwegian:

• bil = car
• bilen = the car

It is a compound noun:

• prøve = test, trial
• periode = period

Together, prøveperiode means trial period, probation period, or testing period, depending on context.

Norwegian uses compound nouns a lot, just like German and sometimes English. Instead of writing two separate words, Norwegian usually joins them into one.

Begynner is the present tense form of the verb å begynne = to begin / to start.

• å begynne = to begin
• begynner = begin(s) / is beginning

So in this sentence:

• Prøveperioden begynner i dag = The trial period begins today

Norwegian present tense is often formed by adding -r or -er to the infinitive stem.

It can mean either, depending on context.

In Norwegian, the simple present often covers both:

• begins
• is beginning

So Prøveperioden begynner i dag could be understood as:

• The trial period begins today
• The trial period is starting today

Usually, English chooses whichever sounds more natural in the situation.

Because prøveperioden already includes the in the ending -en.

English says:

• The trial period

Norwegian says:

• Prøveperioden

So you do not need a separate word for the here.

Also, Norwegian does not need a dummy subject like English it in this sentence. The subject is simply prøveperioden.

In Norwegian, i dag literally means in day, but together it means today.

This is the normal expression:

• i dag = today

Examples:

• Jeg jobber i dag. = I am working today.
• Vi reiser i dag. = We are traveling today.

You just have to learn it as a fixed everyday phrase.

Yes. Norwegian word order is flexible, but the most neutral version here is:

• Prøveperioden begynner i dag.

You can also say:

• I dag begynner prøveperioden.

That version puts more focus on today.

A useful pattern:

• When a time expression like I dag comes first, the verb usually comes next.

So:

• I dag begynner prøveperioden. not
• I dag prøveperioden begynner.

A rough English-friendly guide would be something like:

• PRUH-veh-peh-ree-OO-den
• or more carefully: PRØ-ve-pe-ri-OO-den

A few pronunciation notes:

• ø does not exist in English. It is somewhat like the vowel in French deux or German schön.
• prøve sounds roughly like PRØ-veh
• perioden has the stress mainly on O: pe-ri-OO-den

You do not need perfect pronunciation right away; the most important thing is recognizing the word and saying it consistently.

They are similar, and in many cases both can mean to start or to begin.

• å begynne = to begin / to start
• å starte = to start

In this sentence, begynner sounds very natural.
You could also hear:

• Prøveperioden starter i dag.

That would also be correct in many contexts.

Very roughly:

• begynne can sound a little more like begin
• starte can sound a little more like start

But in everyday usage, they often overlap.

The sentence follows the normal Norwegian pattern:

• Prøveperioden = subject
• begynner = verb
• i dag = time expression

So the structure is:

Subject + Verb + Time

That is a very common Norwegian sentence pattern.

Yes, it is normally treated as a masculine noun:

• en prøveperiode = a trial period
• prøveperioden = the trial period

That is why the definite singular ending is -en.

In Bokmål, many feminine nouns can also be treated as masculine, but prøveperiode is normally learned as masculine.

It sounds neutral and standard.

• It is completely natural in writing.
• It is also natural in speech.
• It is neither especially formal nor especially casual.

So it is a very useful model sentence for everyday Norwegian.