Cortad otra rebanada de pan y traed otra cucharada de salsa, por favor.

Because this sentence is addressing more than one person in Spain, using the vosotros form.

• corta / trae = command to one person (tú)
• cortad / traed = command to more than one person (vosotros)

So:

• Corta otra rebanada... = Cut another slice... (to one person)
• Cortad otra rebanada... = Cut another slice... (to more than one person)

This is very common in Spain. In most of Latin America, speakers would usually use ustedes instead.

For regular affirmative vosotros commands, you usually:

1. take the infinitive
2. remove the final -r
3. add -d

So:

• cortar → cortad
• traer → traed

This is why the sentence says:

• Cortad
• Traed

A useful note: this is the affirmative command form. Negative commands are different:

• No cortéis
• No traigáis

Because the affirmative vosotros command of traer follows the normal pattern:

• traer → traed

Even though traer is irregular in some other forms, its affirmative vosotros command is straightforward here.

Compare:

• traigo = I bring
• trae = bring! (to one person)
• traed = bring! (to more than one person)

So traed is the correct Spain-style plural command.

Because it modifies two different feminine singular nouns:

• otra rebanada
• otra cucharada

The word otro / otra / otros / otras must agree in gender and number with the noun it describes.

Here:

• rebanada is feminine singular → otra
• cucharada is feminine singular → otra

If the nouns were masculine, you would use otro instead.

Because in Spanish, nouns have grammatical gender, and these two nouns are feminine:

• la rebanada
• la cucharada

That is why adjectives and determiners agreeing with them are also feminine:

• otra rebanada
• otra cucharada

This gender is grammatical, not necessarily logical. It is something you usually learn together with the noun.

Here de means of, just as in English:

• rebanada de pan = slice of bread
• cucharada de salsa = spoonful of sauce

This structure is very common in Spanish for quantities and measures:

• un vaso de agua = a glass of water
• un kilo de arroz = a kilo of rice
• una taza de café = a cup of coffee

So de links the measure/container word to the substance or food.

Because after quantity words like rebanada and cucharada, Spanish often uses just de + noun without an article when speaking generally about the substance.

So:

• una rebanada de pan
• una cucharada de salsa

This works like English:

• a slice of bread
• a spoonful of sauce

You could add an article in some contexts, but it would usually sound more specific:

• una rebanada del pan = a slice of the bread
• una cucharada de la salsa = a spoonful of the sauce

The original sentence sounds more natural for a general request.

Rebanada means a slice, especially a fairly flat cut piece, often of bread.

• una rebanada de pan = a slice of bread

Trozo is more general and means piece or chunk.

So:

• rebanada = slice
• trozo = piece

For bread, rebanada is the more precise word if you mean a slice.

Cucharada literally means spoonful or tablespoonful, depending on context.

It comes from cuchara = spoon.

So:

• una cucharada de salsa = a spoonful of sauce

In everyday language, it often refers to the amount that fits in a spoon, not necessarily a precise cooking measurement unless the context is clearly about a recipe.

Because Spanish often omits subject pronouns when they are already clear from the verb form.

Here, the verbs themselves show that the speaker is addressing vosotros:

• cortad
• traed

So you do not need to say vosotros.

You could say:

• Vosotros, cortad otra rebanada...

but that would usually add emphasis, and it is not necessary in normal speech.

Yes. In most of Latin America, speakers would usually use ustedes rather than vosotros for a plural command.

That version would be:

• Corten otra rebanada de pan y traigan otra cucharada de salsa, por favor.

So the original sentence is specifically natural for Spain.

Because por favor is flexible in Spanish. It can appear at the beginning, middle, or end of a polite request.

All of these are possible:

• Por favor, cortad otra rebanada de pan...
• Cortad, por favor, otra rebanada de pan...
• Cortad otra rebanada de pan..., por favor.

Putting it at the end is very common and natural.

Because por favor is being used like a polite parenthetical expression, so it is often separated by a comma.

In writing, this helps show the pause:

• Cortad otra rebanada de pan y traed otra cucharada de salsa, por favor.

In informal writing, people sometimes omit commas, but the comma here is standard and clear.

Yes. Y is the normal Spanish word for and.

So:

• cortad ... y traed ... = cut ... and bring ...

A small extra note: y changes to e before words that begin with an i sound, but that does not apply here.

Grammatically, it is an imperative sentence, so it is a command form. But in real use, adding por favor makes it sound like a polite request.

So although the verbs are commands:

• cortad
• traed

the overall tone is softened by por favor.

In many everyday situations, this would sound perfectly polite rather than harsh.