Ich ziehe die Jalousie runter, weil die Sonne so hell ist.

Because runterziehen is a separable verb.

In a normal main clause, the verb splits:

• Ich ziehe die Jalousie runter.

The conjugated part (ziehe) stays in the usual verb position, and the prefix (runter) moves to the end.

But in the infinitive, it stays together:

• Ich will die Jalousie runterziehen.

This is very common in German with verbs like:

• aufmachen → Ich mache das Fenster auf.
• anmachen → Ich mache das Licht an.

Here, die Jalousie means a blind or window blind.

Depending on region and context, it can refer to:

• indoor blinds
• outdoor shutters/blinds

It does not usually mean a curtain. A curtain is:

• der Vorhang

A related word is:

• der Rollladen = roller shutter

So die Jalousie runterziehen means something like to pull the blind down.

Jalousie is a feminine noun, so its basic article is die.

In this sentence, it is the direct object of ziehen, so it is in the accusative case. For feminine nouns, the article stays die in both nominative and accusative:

• Nominative: die Jalousie
• Accusative: die Jalousie

So:

• Ich ziehe die Jalousie runter.

If it were a masculine noun, you would see a clearer change:

• der Vorhang → Ich ziehe den Vorhang zu.

Because weil introduces a subordinate clause.

In German subordinate clauses, the conjugated verb usually goes to the end:

• ..., weil die Sonne so hell ist.

Compare:

Main clause:

• Die Sonne ist so hell.

Subordinate clause with weil:

• ..., weil die Sonne so hell ist.

This is one of the most important word-order patterns in German.

Other examples:

• Ich bleibe zu Hause, weil ich müde bin.
• Sie geht rein, weil es regnet.

Hell means bright.

So hell here means so bright or that bright. It strengthens the adjective.

• Die Sonne ist hell. = The sun is bright.
• Die Sonne ist so hell. = The sun is so bright.

In everyday English, this may sometimes be translated more naturally as very bright, depending on context. But literally, so means so.

German often uses the definite article with nouns where English sometimes does not, especially with things like:

• die Sonne = the sun
• der Mond = the moon
• die Erde = the earth

So weil die Sonne so hell ist is completely normal German.

English and German do not always use articles in the same way, so this is something you just get used to.

Yes. Runter and herunter are very close in meaning here.

You could say:

• Ich ziehe die Jalousie runter.
• Ich ziehe die Jalousie herunter.

In everyday speech, runter is more common and sounds more casual. Herunter is a bit more full/formal.

Both are correct.

Similarly:

• rauf / herauf
• rein / herein
• raus / heraus

German often uses the present tense where English might use either:

• I pull down the blind or
• I am pulling down the blind

So:

• Ich ziehe die Jalousie runter.

can mean:

• I pull the blind down
• I’m pulling the blind down

German usually does not need a special progressive form like English am pulling.

The exact meaning depends on context.

Because ziehen means to pull, and that fits the physical action of lowering the blind.

• die Jalousie runterziehen = to pull the blind down

German often uses very specific verbs for physical actions. Using machen would be too vague here.

English sometimes says put the blind down, but German commonly says runterziehen because the action is literally pulling it down.

The first clause is:

• Ich ziehe die Jalousie runter

Its structure is:

• Ich = subject
• ziehe = conjugated verb
• die Jalousie = direct object
• runter = separated prefix

So the pattern is:

Subject + verb + object + separable prefix

That is a very common German main-clause pattern.

Yes. German allows that.

You can say:

• Ich ziehe die Jalousie runter, weil die Sonne so hell ist.

Or:

• Weil die Sonne so hell ist, ziehe ich die Jalousie runter.

When the weil clause comes first, the main clause still follows the normal German rule that the conjugated verb comes second:

• ..., ziehe ich ...

So not:

• Weil die Sonne so hell ist, ich ziehe ... ❌

But:

• Weil die Sonne so hell ist, ziehe ich ... ✅

These words are related, but not the same:

• die Jalousie = blind / slatted blind
• der Vorhang = curtain
• der Rollladen = roller shutter

So if you are blocking light with blinds, Jalousie is a good choice. If it is fabric hanging by the window, that is usually Vorhang. If it is the heavy outside shutter that rolls down, that is often Rollladen.

In real life, usage can vary a bit by region and by the kind of window covering being described.