Learn Hardcore Spanish (Spain): Desenchufo la tostadora cuando termino de tostar. - I unplug the toaster when I finish toasting.

In a normal statement you use the conjugated form, because you are saying what the subject does right now or generally. The infinitive desenchufar would be used after another verb or as a noun-like form, e.g. Voy a desenchufar la tostadora (I’m going to unplug the toaster).

Why doesn’t the sentence say yo desenchufo? Where is the subject?

Spanish often drops the subject pronoun (yo, tú, él, etc.) because the verb ending already shows who the subject is.

In desenchufo, the ending -o clearly indicates yo (I), so saying yo desenchufo is usually unnecessary unless you want to emphasize I in contrast to someone else:

Desenchufo la tostadora = I unplug the toaster.
Yo desenchufo la tostadora, no tú = I unplug the toaster, not you.

What tense is desenchufo, and why is the present tense used here?

Desenchufo is present indicative, first person singular (yo).

Here the present is used to express a habitual action: something you normally do whenever a certain situation happens.

Desenchufo la tostadora cuando termino de tostar.
= I (always / usually) unplug the toaster when I finish toasting.

This is the same use of the present as in English sentences like I brush my teeth before bed.

Could I also say apago la tostadora instead of desenchufo la tostadora?

You can say it, but it doesn’t mean exactly the same:

Apagar la tostadora = to turn off the toaster (using its switch/button).
Desenchufar la tostadora = to unplug the toaster (remove the plug from the socket).

If the idea is specifically about safety (physically unplugging it), desenchufo is the accurate verb. If you just mean turning it off, apago would be fine.

Why is it la tostadora and not just tostadora?

Spanish normally uses a definite article (el, la, los, las) with singular countable nouns in cases where English often doesn’t.

So:

Desenchufo la tostadora
literally: I unplug the toaster (the one we’re talking about, understood as “my/the toaster in the kitchen”).

Saying desenchufo tostadora without any article sounds ungrammatical. You could also say mi tostadora (my toaster) if you want to be explicit: Desenchufo mi tostadora.

Why is it tostadora and not tostador?

In Spain, the usual word for a bread toaster is la tostadora (de pan), which is feminine.

la tostadora = the toaster (commonly for bread)
el tostador can be heard in some places or in other countries, and can also refer to other kinds of toasters or roasters, but in everyday Peninsular Spanish la tostadora is the standard term for the kitchen appliance.

So for Spanish from Spain, la tostadora is the most natural choice.

What does cuando termino de tostar literally mean, and how is it functioning grammatically?

Literally, cuando termino de tostar means when I finish toasting.

Breaking it down:

cuando = when
termino = I finish (present indicative, yo)
de = of / (part of a verb pattern)
tostar = to toast (infinitive)

Terminar de + infinitive is a common structure meaning to finish doing something:

terminar de comer = to finish eating
terminar de trabajar = to finish working

So termino de tostar = I finish (the action of) toasting.

Why is it termino de tostar and not termino tostar?

In Spanish, with terminar you normally use the pattern terminar de + infinitive to say finish doing something:

terminar de leer (finish reading)
terminar de estudiar (finish studying)

Saying termino tostar without de is not natural in this meaning. De is required as part of this construction: terminar de + verbo en infinitivo.

Why is tostar (an infinitive) used instead of a noun like tostadas or el pan?

Here, tostar expresses the action of toasting, not the object.

termino de tostar = I finish toasting (whatever I am toasting: bread, slices, etc.)

Using a noun would change the meaning:

termino las tostadas = I finish the toasts / I finish (eating) the toast.
termino el pan = I finish the bread.

With terminar de + infinitive, the focus is on finishing the activity, not the physical thing.

Why is it cuando termino de tostar and not cuando termine de tostar with the subjunctive?

Both forms exist, but they are used in different contexts.

Cuando termino de tostar, desenchufo la tostadora.
→ Present indicative (termino) for habitual or general actions. Every time I finish toasting, I unplug it.
Cuando termine de tostar, desenchufaré la tostadora.
→ Present subjunctive (termine) used with a future reference, often combined with a future verb:
Cuando termine de tostar, la desenchufaré. = When I (have) finished toasting, I’ll unplug it.

In your sentence, you’re describing a regular routine, so the indicative (termino) is correct and natural.

Can I say Desenchufo la tostadora después de tostar instead of cuando termino de tostar?

Yes, you can, and it’s grammatical:

Desenchufo la tostadora después de tostar.
= I unplug the toaster after toasting.

Difference in nuance:

cuando termino de tostar focuses on the moment of finishing.
después de tostar is more general: after toasting (not emphasizing the exact instant of finishing).

Both would be understood in the same everyday way here.

Could I replace la tostadora with la and say La desenchufo cuando termino de tostar?

Yes. Once it’s clear from context that you’re talking about the toaster, you can use a direct object pronoun:

Desenchufo la tostadora cuando termino de tostar.
La desenchufo cuando termino de tostar.

Here la stands for la tostadora (feminine singular). This is very natural in Spanish, especially if la tostadora has already been mentioned earlier in the conversation.