Für das Bild nehme ich Kleber und Buntstifte, weil die Farben besser wirken als auf dem Bildschirm.

It means for the picture or for this artwork/picture project.

In German, für usually expresses purpose or intended use, so Für das Bild tells you what the glue and colored pencils are being used for.

• für = for
• das Bild = the picture/image/artwork

Depending on context, Bild can mean:

• a picture
• an image
• a drawing
• a piece of artwork

Here, it most likely means the picture/art project being made.

Because für always takes the accusative case.

So:

• nominative: das Bild
• accusative: das Bild

Since Bild is neuter, the article stays das in both nominative and accusative singular. That is why you do not see a change here.

Compare with a masculine noun:

• der Bildschirm → für den Bildschirm

That makes the case change easier to notice.

Yes, nehmen literally means to take, but in German it is also often used in the sense of to use, to choose, or to go with, depending on context.

So here:

• ich nehme Kleber und Buntstifte
  = I’m using / I’ll use glue and colored pencils

It sounds natural in German. English usually would not say I take glue and colored pencils in this context, but German can.

Other possible verbs would be:

• ich benutze ... = I use ...
• ich verwende ... = I use/employ ...

But ich nehme ... is very common and idiomatic.

Because Kleber is being used as a general material noun here, like glue in English.

So:

• ich nehme Kleber = I use glue

This is similar to English not always saying a glue.

If you wanted to refer to one specific glue stick, tube, or container, German might use an article, for example:

• ich nehme einen Kleber
• ich nehme den Kleber

But in this sentence, Kleber means glue as a material, so no article is needed.

Buntstifte is the plural of der Buntstift.

It usually means colored pencils.

So:

• der Buntstift = colored pencil
• die Buntstifte = colored pencils

A learner might confuse this with crayons, but Buntstifte usually means pencils with colored cores, not wax crayons. Wax crayons are more typically:

• Wachsmalstifte

Because German main clauses follow the verb-second rule.

That means the finite verb must come in the second position. If you start the sentence with a phrase like Für das Bild, then the verb comes next:

• Für das Bild | nehme | ich ...

So the structure is:

1. Für das Bild
2. nehme
3. ich

English speakers often expect the subject to come first, but German allows other elements in first position as long as the verb stays second.

A more neutral version would be:

• Ich nehme für das Bild Kleber und Buntstifte.

That is also correct.

Because weil introduces a subordinate clause, and in standard German, the conjugated verb goes to the end of that clause.

So:

• weil die Farben besser wirken

The verb wirken comes at the end of the weil clause.

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

• main clause: verb in second position
• subordinate clause: verb at the end

Compare:

• Die Farben wirken besser.
• ..., weil die Farben besser wirken.

Here wirken means something like:

• to look
• to come across
• to appear
• to have an effect

So die Farben besser wirken means the colors look better, come across better, or have a better visual effect.

This is not exactly the same as sein (to be).
German often uses wirken when talking about the impression something creates.

For example:

• Die Farben wirken kräftig. = The colors look vivid.
• Das wirkt modern. = That looks modern / gives a modern impression.

Because the sentence is talking about the colors in the picture/artwork in general, not just one single color.

So:

• die Farbe = the color
• die Farben = the colors

Using the plural makes sense because a picture usually contains several colors, and the speaker is saying that those colors have a better effect when made with glue and colored pencils than when seen on a screen.

Besser is the comparative form of gut:

• gut = good/well
• besser = better

And als is used for comparisons:

• besser als = better than

So:

• die Farben besser wirken als auf dem Bildschirm

means:

• the colors look better than on the screen

This is a standard comparison pattern in German:

• größer als = bigger than
• schneller als = faster than
• schöner als = more beautiful than

Because German, like English, often leaves out words that are understood from context.

The full idea is something like:

• ..., weil die Farben besser wirken, als sie auf dem Bildschirm wirken.

But repeating wirken would sound clumsy, so German shortens it to:

• ..., weil die Farben besser wirken als auf dem Bildschirm.

English does the same thing:

• The colors look better than on the screen instead of
• The colors look better than they look on the screen

So this is a normal elliptical comparison.

Because auf can take either the dative or the accusative, depending on meaning.

• dative = location, no movement
• accusative = movement toward a destination

Here, the meaning is location:

• on the screen

So German uses the dative:

• auf dem Bildschirm

Compare:

• Das Bild ist auf dem Bildschirm. = The image is on the screen.
• Ich lade das Bild auf den Bildschirm. = I load the image onto the screen.

So in your sentence, the colors are being compared with how they appear on the screen, which is a location, so dative is correct.

Yes. In standard German, a subordinate clause introduced by weil must be separated by a comma.

So this is correct:

• ..., weil die Farben besser wirken als auf dem Bildschirm.

German uses commas more systematically than English for clause structure, and this is a very important rule to learn.

Yes, absolutely.

For example:

• Für das Bild benutze ich Kleber und Buntstifte ...
• Für das Bild verwende ich Kleber und Buntstifte ...

All of these are grammatical, but the nuance is slightly different:

• nehmen = choose/use/go with
• benutzen = use
• verwenden = use/employ, sometimes a little more formal

In everyday German, nehmen sounds very natural here.