No dejes la cáscara del huevo sobre la mesa.

No dejes is the negative tú command of dejar.

In Spanish, negative commands for tú use the present subjunctive:

• dejar → dejes
• so: No dejes = Don’t leave

Compare:

• Deja = leave it / put it down (affirmative tú command)
• No dejes = don’t leave it (negative tú command)

So Spanish uses different forms for affirmative and negative tú commands.

In Spanish, negative informal commands are built with the present subjunctive. It is simply the standard pattern:

• Habla → No hables
• Come → No comas
• Vive → No vivas
• Deja → No dejes

So in this sentence, no dejes is not expressing doubt or possibility. It is just the normal grammar for saying don’t ... to one person informally.

This sentence is addressed to one person informally, using tú.

That is why the verb is dejes.

If you changed the person, the sentence would change too:

• No dejes... = don’t leave... (tú)
• No deje... = don’t leave... (usted)
• No dejéis... = don’t leave... (vosotros, common in Spain)
• No dejen... = don’t leave... (ustedes)

Since this is Spanish from Spain, vosotros forms are especially relevant.

Cáscara means the outer covering of something, especially something like an egg, fruit, or nut. Here it means eggshell.

Related words:

• la cáscara del huevo = the shell of the egg / the eggshell
• la piel = skin, peel, or outer skin of a person/fruit
• el cascarón = shell, often specifically an eggshell too, sometimes with a slightly more physical or hard-shell feel

In everyday Spanish, la cáscara del huevo is very natural for the eggshell.

Spanish often includes a of + noun phrase to specify exactly what something belongs to or comes from.

• la cáscara = the shell / peel
• la cáscara del huevo = the shell of the egg / the eggshell

Without del huevo, la cáscara could refer to many things: a banana peel, an orange peel, a nut shell, and so on. Adding del huevo makes it specific.

Because de + el normally contracts to del.

So:

• de el huevo → del huevo

This is one of the two standard Spanish contractions:

• a + el = al
• de + el = del

So la cáscara del huevo literally means the shell of the egg.

Spanish often uses articles more than English does.

Here:

• la cáscara = the shell
• del huevo = of the egg

English often compresses this into a noun phrase like the eggshell, but Spanish commonly keeps the fuller structure:

• la cáscara del huevo

This sounds natural and standard in Spanish.

Here, sobre la mesa means on the table.

Sobre often means:

• on
• over
• above
• sometimes about depending on context

In this sentence, it refers to physical location: the shell is on top of the table.

You could also hear encima de la mesa, which also means on top of the table. In this context, sobre la mesa is perfectly natural.

Sometimes, but it is not exactly the same.

• sobre la mesa = on the table, on its surface
• en la mesa = at the table, on the table, or in the context of the table

If you want to be clearly physical and precise, sobre la mesa is better here because it specifically means the eggshell is resting on the surface.

So for this sentence, sobre la mesa is the more exact choice.

You could say No la dejes sobre la mesa, and that would mean Don’t leave it on the table.

But in the original sentence, the object is stated explicitly:

• la cáscara del huevo

So the sentence does not need a pronoun.

Compare:

• No dejes la cáscara del huevo sobre la mesa. = Don’t leave the eggshell on the table.
• No la dejes sobre la mesa. = Don’t leave it on the table.

Both are correct; the second one only works if it is already clear what it refers to.

Yes, it is natural and correct in Spain.

A few natural alternatives could be:

• No dejes la cáscara del huevo en la mesa.
• No dejes la cáscara de huevo sobre la mesa.
• No dejes el cascarón del huevo sobre la mesa.

But No dejes la cáscara del huevo sobre la mesa is perfectly good Spanish.

In Spain, another possibility if speaking to more than one person informally would be:

• No dejéis la cáscara del huevo sobre la mesa.

In Spain, cáscara is pronounced approximately KAS-ka-ra.

A few helpful points:

• The stress is on the first syllable: CÁS-ca-ra
• The c before a sounds like k
• The r in cáscara is a single tapped r, not a long trilled one

The written accent mark in cáscara shows where the stress goes.

In Spanish, h is normally silent, so huevo is pronounced roughly like WEH-bo in Spain.

Even though the h is not pronounced, it still appears in spelling because it is part of the standard written form of the word.

So:

• written: huevo
• pronounced: roughly WEH-bo

In Spain, the v/b sound in huevo is the normal Spanish b/v sound, not a strong English v.

In theory, de can mean several things, including of, from, or about, depending on context. But here, la cáscara del huevo is understood as the shell of the egg.

It describes what kind of shell it is, not where it is coming from physically at that moment.

So in this sentence, the natural meaning is clearly the eggshell.

Here are the most useful versions:

• No dejes la cáscara del huevo sobre la mesa. = tú
• No deje la cáscara del huevo sobre la mesa. = usted
• No dejéis la cáscara del huevo sobre la mesa. = vosotros (very common in Spain)
• No dejen la cáscara del huevo sobre la mesa. = ustedes

If you are learning Spanish from Spain, the vosotros form is especially worth remembering.