Cuando termino de cocinar, dejo el delantal sobre la silla y guardo el salero, la espátula y el pimentero en el cajón.

In Spanish, subject pronouns are often omitted because the verb ending already shows who the subject is.

• termino = I finish
• dejo = I leave
• guardo = I put away / store

So yo is unnecessary unless you want extra emphasis or contrast:

• Yo termino de cocinar, pero tú no. = I finish cooking, but you don’t.

After terminar, Spanish normally uses de + infinitive when you mean to finish doing something.

• terminar de cocinar = to finish cooking
• terminar de leer = to finish reading
• terminar de limpiar = to finish cleaning

So termino de cocinar is the standard structure.

Be careful: acabar de + infinitive means to have just done something, which is different:

• Acabo de cocinar = I’ve just cooked / I just finished cooking

Spanish often uses the present tense to talk about habitual actions, just like English does.

• Cuando termino de cocinar, dejo... y guardo... = When I finish cooking, I leave... and put away...

This describes what the speaker generally does every time, not just one specific moment.

Because Cuando termino de cocinar is an introductory subordinate clause. In Spanish, it is very common to place a comma after this kind of opening clause.

• Cuando termino de cocinar, dejo el delantal...

It works much like English:

• When I finish cooking, I leave the apron...

They are not the same action.

• dejo el delantal sobre la silla = I leave the apron on the chair
• guardo el salero, la espátula y el pimentero en el cajón = I put away / store the salt shaker, spatula, and pepper shaker in the drawer

So:

• dejar = to leave, to set something somewhere
• guardar = to put away, store, keep

Using two different verbs makes the sentence more natural because the apron is being left on the chair, while the other items are being put back in the drawer.

Sobre means on or on top of, which fits the idea of the apron resting on the chair.

• sobre la silla = on the chair

En la silla usually means in/on the chair in a broader location sense, but for an object physically placed on top of a surface, sobre is more precise.

In everyday Spanish, some speakers might also say en la silla in certain contexts, but sobre la silla clearly emphasizes physical placement on top.

Because all the listed objects are going into the same drawer.

• guardo el salero, la espátula y el pimentero en el cajón = I put the salt shaker, the spatula, and the pepper shaker in the drawer

The phrase en el cajón applies to the whole list.

In Spanish, it is very common to repeat the definite article before each noun in a list, especially when referring to specific items.

• el salero, la espátula y el pimentero

This sounds natural and clear in Spanish. English often drops repeated the, but Spanish frequently keeps it.

You might sometimes see articles omitted in other contexts, but here repeating them is completely normal.

They usually refer to the containers used for salt and pepper.

• el salero = salt shaker / salt cellar
• el pimentero = pepper shaker

In Spain, pimienta is pepper, so pimentero is the pepper container. Be careful not to confuse pimiento (pepper as a vegetable) with pimienta (pepper as a spice).

Because delantal is a masculine noun in Spanish.

• el delantal = the apron

Its ending does not determine its gender here. While many nouns ending in -a are feminine and many ending in -o are masculine, nouns ending in other letters must often just be learned with their article.

Always learn nouns together with their article:

• el delantal
• la espátula
• el cajón

Espátula has a written accent because the stress falls on spá:

• es-PÁ-tu-la

Without the accent, normal pronunciation rules would suggest a different stress pattern. The accent mark shows the correct stressed syllable.

Cajón is stressed on the last syllable:

• ca-JÓN

Words ending in n, s, or a vowel are normally stressed on the second-to-last syllable unless they have a written accent. The accent mark tells you that this word is stressed on the final syllable.

Sometimes, but it changes the nuance.

• pongo ... en el cajón = I put ... in the drawer
• guardo ... en el cajón = I put away / store ... in the drawer

Guardo suggests returning the items to where they belong. Pongo is more neutral and just focuses on placing them there.

In this sentence, guardo sounds more natural because kitchen tools are being tidied away after cooking.

Here it can naturally express a habitual meaning, close to whenever.

• Cuando termino de cocinar, ... = When / Whenever I finish cooking, ...

Because the rest of the sentence is in the present tense and describes a routine, English could understand it as habitual.

A natural pronunciation would be roughly:

CUAN-do ter-MI-no de co-ci-NAR, DE-jo el de-lan-TAL SO-bre la SI-lla y GUAR-do el sa-LE-ro, la es-PÁ-tu-la y el pi-men-TE-ro en el ca-JÓN.

A few useful notes:

• cuando: the cuan- part sounds like kwan
• cocinar: final stress on -nar
• espátula: stress on spá
• cajón: stress on the last syllable

In many parts of Spain, c before i/e and z are pronounced with a th sound:

• cocinar: the c before i may sound like th
• espátula has a normal t, not that sound

Yes, somewhat, but the original order is very natural.

Original:

• Cuando termino de cocinar, dejo el delantal sobre la silla y guardo el salero, la espátula y el pimentero en el cajón.

You could rearrange parts for emphasis, for example:

• Cuando termino de cocinar, guardo en el cajón el salero, la espátula y el pimentero...

But the given version is smooth and standard. The main thing is to keep the meaning clear: the apron goes on the chair, and the other items go in the drawer.