El enchufe está arriba, así que pongo la silla debajo para enchufar el portátil.

In this sentence el enchufe most naturally means the wall socket / power outlet (where you plug something in), especially in Spain.
It can also mean plug (the part on the cable), but in context (Está arriba + needing a chair) it’s clearly referring to a socket placed high up.

Spanish uses estar (not ser) for location/position. So está arriba = it is up high / up there.
Ser is more about identity or inherent characteristics (e.g., Es un enchufe viejo = It’s an old socket/plug).

Arriba is an adverb meaning up / up there / upstairs / up high depending on context. Here it’s up high (e.g., higher on the wall).
If you wanted something more explicit you might say está muy alto (it’s very high) or está en alto (it’s placed high up).

Así que means so / therefore / as a result and introduces a consequence:
El enchufe está arriba, así que… = The outlet is high up, so…
Entonces can also mean so/then, but así que often feels more clearly “cause → result” in one sentence.

Spanish often uses the simple present to describe actions that are happening now or are the natural next step in a situation: pongo la silla = I put/I'm putting the chair.
If you want to emphasize intention/immediacy, you can say voy a poner la silla (I’m going to put the chair).

• poner = a very general to put/place (most common everyday choice).
• colocar = to place/position (a bit more deliberate/formal).
• meter = to put inside (doesn’t fit well here because the chair isn’t going into something).
  So pongo la silla debajo is the natural everyday phrasing.

Spanish can omit the complement after debajo when it’s obvious from context. Here, debajo is understood as debajo del enchufe (under the socket).
If you want to be explicit: pongo la silla debajo del enchufe.

Para expresses purpose/goal:

• para enchufar el portátil = in order to plug in the laptop.
  Por is used for reasons/causes in other patterns (e.g., Gracias por enchufarlo = Thanks for plugging it in), but not for “in order to.”

Enchufar means to plug in (connect a device to electricity by putting the plug into the socket).
So enchufar el portátil = to plug in the laptop (so it can charge/run on mains power).

Yes. In Spain, (ordenador) portátil is very common. People often just say el portátil if it’s clear they mean a laptop.
In much of Latin America you’ll also hear laptop or computadora portátil.

• así has an accent to mark stress and to distinguish it from asi (which isn’t normally used in standard Spanish).
• portátil has an accent because the stress falls on -til (por-ta-TIL). Words stressed on the last syllable (agudas) take an accent when they end in n, s, or a vowel—here it ends in l, so the accent is for the stress pattern of portátil (it’s actually stressed on the second-to-last? In practice: por-TA-til is common in speech, but standard stress is marked by the written accent, so you follow it when pronouncing).