Rehabiliteringen starter i morgen.

Because -en is the definite singular ending for many Norwegian nouns.

• rehabilitering = rehabilitation
• rehabiliteringen = the rehabilitation

In Norwegian, the definite article is often attached to the end of the noun instead of being a separate word like English the.

Norwegian usually puts the definite article on the noun itself.

So instead of saying something like the rehabilitation, Norwegian says rehabiliteringen.

This is very common:

• bil = car

• bilen = the car

• bok = book
• boka / boken = the book

So rehabiliteringen already includes the idea of the.

starter is the present tense of starte.

• å starte = to start
• starter = starts / is starting / start, depending on context

In Norwegian, the present tense is often made by adding -r to the infinitive:

• å snakke → snakker
• å bo → bor
• å starte → starter

No. Norwegian verbs do not change for person the way English verbs do.

For example, with starte:

• jeg starter = I start
• du starter = you start
• han starter = he starts
• vi starter = we start

The verb form starter stays the same.

i morgen is the normal Norwegian expression for tomorrow.

Even though i often means in, the whole phrase i morgen functions as a fixed time expression meaning tomorrow.

Be careful not to confuse it with similar expressions:

• i morgen = tomorrow
• om morgenen = in the morning

So in this sentence, i morgen means the day after today, not morning time.

Yes. You can also say:

I morgen starter rehabiliteringen.

That still means the same thing.

This is because Norwegian follows the V2 rule in main clauses: the finite verb usually comes in the second position.

So:

• Rehabiliteringen starter i morgen.
• I morgen starter rehabiliteringen.

Both are correct, but the second version puts more emphasis on tomorrow.

Norwegian often uses the present tense for future events when the time is already clear from context.

Here, i morgen makes it obvious that the event is in the future, so starter is enough.

This is very normal in Norwegian:

• Jeg reiser i morgen. = I’m leaving tomorrow.
• Møtet begynner klokka ni. = The meeting starts at nine.

You can use future-marking words like skal in some situations, but they are not necessary here.

Yes, often it could.

• starter = starts
• begynner = begins

In many contexts, both are natural:

• Rehabiliteringen starter i morgen.
• Rehabiliteringen begynner i morgen.

There can be small stylistic differences, but in a sentence like this, both are very common and acceptable.

It is a common gender noun in Norwegian, which is why the definite singular form is rehabiliteringen.

A useful pattern is:

• indefinite singular: en rehabilitering
• definite singular: rehabiliteringen

Many abstract nouns ending in -ing work like this.

A careful approximation is:

reh-ah-bih-li-teh-RING-en STAR-ter ee MOR-en

A few helpful points:

• r is usually pronounced more clearly than in many English accents
• i in i morgen sounds like a long ee
• morgen is often pronounced roughly like MOR-en in everyday speech, with the middle consonants less strongly pronounced than an English speaker might expect

If you want to sound natural, keep the rhythm fairly even and stress starter and morgen more than the other parts.