Hvis jeg bliver træt, vil jeg slukke lyset og gå i seng.

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Breakdown of Hvis jeg bliver træt, vil jeg slukke lyset og gå i seng.

• og: and
• blive: to become
• lyset: the light

Questions & Answers about Hvis jeg bliver træt, vil jeg slukke lyset og gå i seng.

Why does the sentence start with Hvis, and what kind of clause is Hvis jeg bliver træt?

Hvis means if and introduces a conditional subordinate clause.
So Hvis jeg bliver træt is the “condition” part: If I get tired …
The rest (vil jeg …) is the “main clause” that tells what will happen if the condition is met.

Why is there a comma after træt?

In Danish, it’s standard to put a comma between a subordinate clause and the main clause:
Hvis jeg bliver træt, vil jeg …
You’ll often see this even in relatively short sentences.

Why is the word order vil jeg and not jeg vil?

Because the sentence begins with something other than the subject (Hvis…), Danish uses V2 word order in the main clause: the finite verb comes in second position.
Main clause: vil (finite verb) + jeg (subject) + rest
So: …, vil jeg slukke lyset …
If the main clause stood alone, you’d normally say Jeg vil slukke lyset …

What does bliver mean here—why not use er?