Nå som putevaret er tørt, kan jeg legge meg.

Nå som means now that in this sentence.

It introduces a reason or situation that has just become true:

• Nå som putevaret er tørt ... = Now that the pillowcase is dry ...

It is a very common way to connect two ideas when one new fact affects what happens next.

Examples:

• Nå som du er her, kan vi begynne. = Now that you’re here, we can start.
• Nå som det er sommer, vil jeg bade. = Now that it’s summer, I want to swim.

So here, the idea is: the pillowcase is dry now, and because of that, the speaker can go lie down / go to bed.

Putevar is the indefinite form: a pillowcase.
Putevaret is the definite form: the pillowcase.

This noun is neuter:

• et putevar = a pillowcase
• putevaret = the pillowcase

Norwegian often uses the definite form where English might also use the, especially when talking about a specific item already understood from context.

Also, putevar is a compound noun:

• pute = pillow
• var = cover/case

So putevaret literally means the pillow-cover / the pillowcase.

Because tørt has to agree with putevaret, which is a neuter singular noun.

The adjective is:

• tørr = dry

But its forms change depending on grammar:

• en tørr sokk = a dry sock
• et tørt putevar = a dry pillowcase
• sokkene er tørre = the socks are dry

In this sentence, the adjective comes after er and describes putevaret, so it still agrees with the noun:

• putevaret er tørt = the pillowcase is dry

The spelling change from tørr to tørt is just part of how this adjective forms the neuter.

Because the sentence starts with a subordinate clause:

• Nå som putevaret er tørt

After that, the main clause follows, and Norwegian uses verb-second word order in main clauses. That means the finite verb comes before the subject when something else comes first.

So:

• Jeg kan legge meg. = I can go to bed.
• Nå som putevaret er tørt, kan jeg legge meg. = Now that the pillowcase is dry, I can go to bed.

The first part takes the first position, so the verb kan comes next, then the subject jeg.

This inversion is very important in Norwegian.

Legge meg means lie down, go to bed, or turn in, depending on context.

The verb is å legge seg, which is a reflexive verb:

• å legge seg = to lie down / go to bed

The seg changes depending on the subject:

• jeg legger meg
• du legger deg
• han legger seg

So in the sentence:

• kan jeg legge meg = can I go lie down / can I go to bed

The word meg is necessary because this verb is normally used reflexively when talking about a person putting themselves into a lying/resting position.

This is a very common question.

• å legge seg = to lie down / go to bed
  
  • focuses on the action of moving into a lying position
• å ligge = to be lying / to lie
  
  • focuses on the state of already being in that position

Compare:

• Jeg skal legge meg. = I’m going to lie down / go to bed.
• Jeg ligger i senga. = I am lying in bed.

So in your sentence, legge meg is used because the speaker is about to do the action of going to bed, not just describing their position.

Because the sentence begins with a subordinate clause:

• Nå som putevaret er tørt

In Norwegian, it is normal to put a comma between a subordinate clause and the following main clause:

• Nå som putevaret er tørt, kan jeg legge meg.

This helps show the structure clearly:

1. subordinate clause: Now that the pillowcase is dry
2. main clause: I can go to bed

So the comma is standard and correct.

No, here it is not a question.

In Norwegian main clauses, when something other than the subject comes first, the verb comes before the subject. That creates the order:

• kan jeg

But this is still a statement because of the full sentence structure and punctuation:

• Nå som putevaret er tørt, kan jeg legge meg.

A real question would usually stand on its own and use question intonation or a question mark:

• Kan jeg legge meg? = Can I go to bed?

So in your sentence, kan jeg just reflects normal Norwegian word order after a fronted clause.

Yes, but it is slightly different.

• putevaret er tørt = the pillowcase is dry
  
  • focuses on the current state
• putevaret har tørket = the pillowcase has dried
  
  • focuses more on the process/result of drying

Both can work in many contexts, but er tørt sounds very natural when the important thing is simply that it is dry now.

So:

• Nå som putevaret er tørt, kan jeg legge meg.
• Nå som putevaret har tørket, kan jeg legge meg.

Both are possible, but the first one is often the more straightforward way to describe the situation.