Learn Hardcore Portuguese (Portugal): A extensão está atrás da secretária; liga o portátil aí à tomada. - The extension is behind the desk; plug the laptop into the socket there.

In Portugal, a extensão normally means an extension lead/cord, often with multiple sockets. If it’s the bar-style strip, people also say a régua (power strip). You might also hear:

extensão elétrica (neutral/explicit)
tripla (a 3‑outlet adapter)
benjamim (small multi-plug adapter)

Is secretária a desk or a female secretary?

Here it means a desk (the piece of furniture). The same word can mean a female secretary (person), but context disambiguates. For a male secretary it’s o secretário. If you mean a generic table, that’s a mesa.

Why is it atrás da secretária and not “atrás de a secretária”?

Because atrás de requires the preposition de, and Portuguese contracts preposition + article:

de + a = da (atrás da secretária)
de + o = do
de + as = das
de + os = dos

Could I say atrás da mesa instead of atrás da secretária?

Only if you really mean a table. Secretária is specifically a desk. Mesa is a broader “table,” not necessarily a workstation/desk.

Why está and not é or fica?

estar is used for location: A extensão está atrás da secretária.
ser is not used for physical location.
ficar can also express location (“is located”): A extensão fica atrás da secretária. It can sound a bit more like “is situated/ends up.”

What form is liga? Which person is being addressed?

Liga is the affirmative imperative for tu (informal singular) of ligar.

tu: liga; negative: não ligues
você (formal sg.): ligue; negative: não ligue
vocês (plural): liguem; negative: não liguem

Why is there no subject pronoun (no tu)?

Portuguese normally drops subject pronouns, and the imperative doesn’t take a stated subject in direct commands. The verb form itself shows who is addressed.

What does aí mean here, and how does it differ from aqui, ali, and lá?

aqui = here (near the speaker)
aí = there (near the listener)
ali = there (a short distance from both)
lá = over there/there (farther away or more abstract) In the sentence, aí means “there where you are.”

Where can aí go in the sentence? Is Liga aí o portátil à tomada okay?

Yes. In instructions, placing short adverbs like aí right after the verb is very natural: Liga aí o portátil à tomada. The original order (Liga o portátil aí à tomada) is also fine. Ending with ...à tomada aí is unusual in Portugal.

Why à tomada with a grave accent?

It’s the contraction of the preposition a + the feminine article a: a + a tomada = à tomada. With plurals: às tomadas. In Portugal it’s idiomatic to say ligar à tomada/à corrente. The Brazilian ligar na tomada (em + a) is common in Brazil but not in Portugal.

Is tomada the plug or the socket?

In Portugal:

a tomada = the wall socket/outlet
a ficha = the plug attached to the cable So you plug the ficha into the tomada.

Is o portátil really how you say “laptop” in Portugal?

Yes. o portátil is very common (short for computador portátil). You’ll also hear o computador portátil. The English loanword laptop exists but is less standard. notebook is more Brazilian.

Could I replace o portátil with a pronoun? How?

Yes. Use an enclitic pronoun in the affirmative imperative:

Liga-o à tomada. (Plug it into the socket.) In the negative, it goes before the verb and the form changes:
Não o ligues à tomada.

Is the semicolon necessary? Could I use a period?

A period is perfectly fine: A extensão está atrás da secretária. Liga o portátil aí à tomada. The semicolon simply links two closely related clauses more tightly. A comma would be less formal and not ideal in standard writing.

Are there alternatives to atrás de, like detrás or por detrás de?

Yes:

atrás de = the neutral, most common choice
por detrás de = a bit more explicit/emphatic
detrás alone is possible but less common in everyday speech

Why is it a extensão (feminine)? I thought many -ão nouns are masculine.

Many -ão nouns are masculine, but not all. Nouns ending in -ção/-são (often from Latin -tion/-sion) are typically feminine: a canção, a nação, a extensão. You just have to learn each noun’s gender.

Does ligar mean “to call” on the phone too?

Yes. Ligar para alguém = to call someone. It also means “to turn on” a device (ligar o portátil) and “to connect” something a/à something (ligar o portátil à tomada). The preposition helps show the meaning.

Any quick pronunciation tips for tricky bits like aí and extensão?

aí has two syllables: a‑Í (like “ah-EE”), stress on the second.
extensão ends with nasal -ão (a nasalized “ow” sound). The ç is an “s” sound: ehs-ten-SÃO.
secretária stresses the tá: se-cre-TÁ-ria.
portátil stresses the tá: por-TÁ-til.