Ich lege das Schneidebrett auf den Tisch, bevor ich die Paprika schneide.

Legen is the normal verb for put/lay something so that it ends up lying flat.

That fits a cutting board well, because a cutting board is typically placed flat on a table.

German often distinguishes these verbs more clearly than English:

• legen = put something so it lies
• stellen = put something so it stands
• setzen = seat/set someone or something in a sitting position

So das Schneidebrett auf den Tisch legen sounds very natural.

Schneidebrett is a neuter noun, so its article is das.

It is also a compound noun:

• schneiden = to cut
• Brett = board

In German compounds, the last part usually determines the gender, and Brett is neuter, so:

• das Brett
• das Schneidebrett

In this sentence, das Schneidebrett is also the direct object of lege, so it is in the accusative. But for neuter singular nouns, the nominative and accusative article are both das, so the form does not change.

Because auf is a two-way preposition.

With two-way prepositions, German uses:

• accusative for movement toward a destination
• dative for location

Here, the cutting board is being moved onto the table, so German uses the accusative:

• auf den Tisch

If you were describing where it already is, you would use the dative:

• Das Schneidebrett liegt auf dem Tisch.

So the contrast is:

• Ich lege das Schneidebrett auf den Tisch. → movement
• Das Schneidebrett liegt auf dem Tisch. → location

Bevor is used before a clause with a verb. Vor is used before a noun phrase.

So:

• bevor ich die Paprika schneide = before I cut the pepper
• vor dem Schneiden = before the cutting
• vor dem Essen = before the meal / before eating

A useful rule:

• bevor
  • subject + verb clause
• vor
  • noun

You cannot say vor ich die Paprika schneide in standard German; it must be bevor.

Because bevor introduces a subordinate clause, and in German subordinate clauses the conjugated verb goes to the end.

So:

• main clause: Ich lege das Schneidebrett auf den Tisch
• subordinate clause: bevor ich die Paprika schneide

That final schneide is still fully conjugated:

• infinitive: schneiden
• ich schneide

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

• after subordinating conjunctions like bevor, weil, dass, wenn, obwohl, the verb goes to the end.

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

So the comma before bevor is required:

• Ich lege das Schneidebrett auf den Tisch, bevor ich die Paprika schneide.

This is stricter than English, where commas can sometimes be more flexible. In German, with a subordinate clause like this, the comma is standard and expected.

Here, Paprika is the feminine singular noun, so the article is die.

In this sentence, it clearly means the vegetable—a bell pepper / sweet pepper—because it is being cut.

That can confuse English speakers, because English paprika usually means the spice. In German:

• die Paprika often means the vegetable
• the spice can also be called Paprika, but context usually makes it clear
• Paprikapulver is a more explicit word for paprika powder

Also, in this sentence die Paprika is the direct object of schneide, so it is in the accusative. Since feminine singular uses die in both nominative and accusative, the article stays the same.

Here is the case breakdown:

• Ich = nominative
  It is the subject of lege and also the subject of schneide.

• das Schneidebrett = accusative
  It is the direct object of lege.

• den Tisch = accusative
  It follows auf and shows movement toward a destination.

• die Paprika = accusative
  It is the direct object of schneide.

So this sentence is a good example of how German uses case both for:

• direct objects
• prepositions that can take more than one case

Yes, in a way.

German often uses the present tense for:

• things happening now
• habitual actions
• near-future actions
• sequences of actions, when the timing is already clear

Here, the order of actions is clear from bevor, so German does not need a special future form.

This is very normal German. You do not need werde legen or werde schneiden here.

Yes. You can say:

Bevor ich die Paprika schneide, lege ich das Schneidebrett auf den Tisch.

That is completely correct.

But when the subordinate clause comes first, the main clause still follows the verb-second rule. Since the first position is already taken by the whole bevor clause, the verb comes immediately after it:

• Bevor ich die Paprika schneide, lege ich ...

Not:

• Bevor ich die Paprika schneide, ich lege ...

So the finite verb lege must come before ich in the main clause.