Bevor ich weiterzeichne, spitze ich den Buntstift mit dem Spitzer.

Because bevor is a subordinating conjunction. In German, when a clause starts with a subordinating conjunction such as bevor (before), the conjugated verb goes to the end of that clause.

So:

• Bevor ich weiterzeichne = Before I continue drawing
• not Bevor ich zeichne weiter

This is a very common German pattern:

• Wenn ich Zeit habe, ...
• Weil er müde ist, ...
• Bevor ich weiterzeichne, ...

In all of those, the verb in the subordinate clause comes last.

Because the sentence begins with the subordinate clause:

• Bevor ich weiterzeichne,

When a subordinate clause comes first, it takes up the first position in the sentence. In German main clauses, the conjugated verb must still be in second position, so the next thing must be the verb:

• Bevor ich weiterzeichne, spitze ich den Buntstift ...

This is called verb-second word order in the main clause.

Compare:

• Ich spitze den Buntstift, bevor ich weiterzeichne.
• Bevor ich weiterzeichne, spitze ich den Buntstift.

Both are correct, but when the bevor clause comes first, spitze must come before ich.

Here weiterzeichnen is being treated as a single verb, meaning to continue drawing.

So:

• weiterzeichnen = to keep drawing / continue drawing
• ich zeichne weiter = I continue drawing

In practice, German often allows both a separated and a combined version depending on structure and style:

• Ich zeichne weiter.
• Bevor ich weiterzeichne, ...

In a clause where the verb goes to the end, it is very natural to see it written together as weiterzeichne.

Here weiter means further, on, or continuing. In this sentence, it gives the idea of carrying on with the drawing.

So weiterzeichnen means:

• to continue drawing
• to draw on
• to keep drawing

It does not mean drawing something wider or farther away here. It is about continuation of the action.

Because Buntstift is the direct object of spitzen.

The verb spitzen means to sharpen, and the thing being sharpened is the direct object, which takes the accusative case.

• nominative: der Buntstift
• accusative: den Buntstift

So:

• Ich spitze den Buntstift. = I sharpen the colored pencil.

This happens because Buntstift is masculine:

• der → den in the accusative

Because the preposition mit always takes the dative case.

So:

• der Spitzer = the sharpener
• after mit → dem Spitzer

That is why German says:

• mit dem Spitzer = with the sharpener

A useful rule to remember is:

• mit + dative

Examples:

• mit dem Messer = with the knife
• mit der Schere = with the scissors
• mit dem Spitzer = with the sharpener

They are two different nouns:

• der Buntstift = colored pencil
• der Spitzer = pencil sharpener

So in the sentence:

• den Buntstift is the thing being sharpened
• mit dem Spitzer tells you the tool used to sharpen it

This is the same basic idea as:

• I cut the bread with the knife
• Ich schneide das Brot mit dem Messer

Because the two verbs work differently.

• zeichnen = to draw
• weiterzeichnen = to continue drawing

So weiter modifies zeichnen and creates the meaning continue drawing.

But spitzen is already a complete verb by itself meaning to sharpen. It does not need an extra word here.

So the sentence means:

• first action: sharpening
• later action: continuing to draw

German often uses the present tense to describe actions in a sequence when the timing is clear from words like bevor.

So:

• Bevor ich weiterzeichne, spitze ich den Buntstift.

literally uses present tense in both clauses, but the word bevor already makes the order clear:

1. sharpen the pencil
2. continue drawing

This is normal German usage. English often does something similar:

• Before I continue drawing, I sharpen the colored pencil.

Even though one thing happens first, both verbs can still be in the present tense.

Because German normally uses a comma to separate a subordinate clause from the main clause.

Here:

• Bevor ich weiterzeichne, = subordinate clause
• spitze ich den Buntstift mit dem Spitzer. = main clause

German punctuation is stricter than English in this area. With clauses introduced by words like weil, dass, wenn, bevor, and many others, the comma is usually required.

You may sometimes see variation depending on style and structure, but in a sentence like this, weiterzeichne as one word is the standard and safest choice.

So for a learner, it is best to use:

• Bevor ich weiterzeichne, ...

In other structures, you often see the parts separated:

• Ich zeichne weiter.

That is a common pattern in German: some verb combinations appear joined in one place and separated in another.

Yes. Einen Stift spitzen is normal German and means to sharpen a pencil/pencil-like writing tool.

So:

• Ich spitze den Bleistift. = I sharpen the pencil.
• Ich spitze den Buntstift. = I sharpen the colored pencil.

In everyday speech, this is a very natural choice.

Yes. A very common alternative is:

• Ich spitze den Buntstift mit dem Spitzer, bevor ich weiterzeichne.

This means the same thing. The difference is mainly focus and style:

• Bevor ich weiterzeichne, spitze ich den Buntstift ... puts the time relationship first.
• Ich spitze den Buntstift ..., bevor ich weiterzeichne. starts with the main action.

Both are grammatically correct.

A good pattern to copy is:

• Bevor + subject + verb-at-the-end, main verb + subject + rest

For example:

• Bevor ich esse, wasche ich mir die Hände.
• Bevor er ausgeht, schließt er das Fenster.
• Bevor wir anfangen, lesen wir die Anleitung.

So in your sentence:

• Bevor ich weiterzeichne, spitze ich den Buntstift mit dem Spitzer.

Key things to remember:

• bevor sends the verb to the end of its clause
• if that clause comes first, the main-clause verb comes before the subject
• mit takes the dative
• the direct object takes the accusative