Am Abend ziehe ich den Rollladen runter und fasse die Türklinke nur kurz an.

Am Abend means in the evening or in the evening time.

A few grammar points are packed into it:

• am = an dem
• After an in this time expression, German uses the dative
• Abend is masculine, so dem Abend is correct

So:

• am Morgen = in the morning
• am Nachmittag = in the afternoon
• am Abend = in the evening

This is just a very common German time expression. English uses in the evening, but German usually says am Abend.

Because German main clauses usually follow the verb-second rule.

In this sentence, Am Abend has been moved to the front. That fronted time phrase takes the first position, so the finite verb must come next:

• Am Abend = position 1
• ziehe = position 2
• ich comes after that

So:

• Ich ziehe am Abend den Rollladen runter.
• Am Abend ziehe ich den Rollladen runter.

Both are correct, but the second version emphasizes when it happens.

Because Rollladen is the direct object of ziehen here, so it is in the accusative case.

The noun Rollladen is masculine:

• nominative: der Rollladen
• accusative: den Rollladen

So:

• Ich ziehe den Rollladen runter.

The person doing the action is ich, and the thing being pulled down is den Rollladen.

runterziehen is a separable verb. It means to pull down.

In a normal present-tense main clause, separable verbs split apart:

• Ich ziehe den Rollladen runter.

Here:

• ziehe = the main verb part
• runter = the separable prefix, placed at the end of the clause

Compare:

• infinitive: runterziehen
• present tense: ich ziehe ... runter
• perfect: ich habe ... runtergezogen

This is very common in German:

• aufmachen → Ich mache die Tür auf.
• anmachen → Ich mache das Licht an.

A Rollladen is a roller shutter or rolling blind on the outside of a window. It is usually pulled down for darkness, privacy, or security.

It is not exactly the same as:

• der Vorhang = curtain
• die Jalousie = Venetian blind / slatted blind

So den Rollladen runterziehen specifically suggests pulling down that outside shutter.

Because the subject ich is understood from the first clause and does not have to be repeated.

The full version could be:

• Am Abend ziehe ich den Rollladen runter und ich fasse die Türklinke nur kurz an.

But German often leaves out the repeated subject when it is the same:

• Am Abend ziehe ich den Rollladen runter und fasse die Türklinke nur kurz an.

That sounds natural and efficient.

Because anfassen is also a separable verb. It means to touch or to handle.

In the infinitive:

• anfassen

In a present-tense main clause:

• Ich fasse die Türklinke an.

So in your sentence:

• fasse is the finite verb
• an goes to the end of the clause

This works the same way as runterziehen in the first half of the sentence.

Yes, it is accusative too, because it is the direct object of anfassen.

But die looks the same in both nominative and accusative for feminine nouns:

• nominative: die Türklinke
• accusative: die Türklinke

So the case does not visibly change here, unlike with masculine nouns such as:

• der Rollladen → den Rollladen

That is why one object changes form and the other does not.

nur kurz means only briefly, just for a moment, or only for a short time.

• nur = only / just
• kurz = briefly / for a short time

So:

• Ich fasse die Türklinke nur kurz an. = I touch the door handle only briefly.

It tells you that the touching is very short.

Because with a separable verb in a main clause, the prefix usually goes to the end of the clause.

So even though an belongs with fasse, other elements can appear before it:

• Ich fasse die Türklinke an.
• Ich fasse die Türklinke nur kurz an.

The adverb phrase nur kurz comes before the final separable prefix an.

This is normal German word order.

Grammatically, it is in the present tense, but in German the present tense can express different things depending on context.

Here, because of Am Abend, it often sounds like a habit or routine:

• In the evening, I pull down the shutter and only touch the door handle briefly.

So it can mean something like this is what I do in the evening.

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

• the simple present for habits
• or the present progressive for something happening now, depending on context

Yes. runterziehen and herunterziehen are very close in meaning.

• runter is a bit more colloquial
• herunter can sound a little fuller or slightly more formal/neutral

So both of these are possible:

• Ich ziehe den Rollladen runter.
• Ich ziehe den Rollladen herunter.

In everyday spoken German, runter is very common.