Lo importante es que cierres sesión antes de apagar el portátil.

Lo is the neuter article in Spanish. It’s used to turn an adjective (or an idea) into an abstract noun:

• lo importante = the important thing / what’s important (an abstract concept) You can’t use el/la here because importante isn’t a masculine/feminine noun; it’s an adjective being “nominalized” by lo.

Lo importante es que + clause is a very common way to highlight what matters most:

• Lo importante es que cierres sesión… = The important thing is that you log out… It works like a “topic + explanation” structure: first you state the key point (lo importante), then you specify it with a clause introduced by que.

Because es importante que… triggers the subjunctive: it expresses importance/necessity, not a statement of fact.

• Es importante que cierres… → subjunctive (desired/required action) If you used indicative (cierras), it would sound like you’re stating a fact (“it’s important that you do (indeed) log out”), which is not the normal intent here.

cierres is present subjunctive, 2nd person singular (tú) of cerrar.

• Indicative: tú cierras
• Subjunctive: (que) tú cierres

Yes—the present subjunctive form for usted is the same here:

• Es importante que cierres sesión… (tú)
• Es importante que cierre sesión… (usted) So with usted, it would change to cierre (not cierres).

In tech contexts, Spanish often uses cerrar sesión as a fixed expression meaning to log out (like an action label in an interface). It commonly appears without an article. You may also see:

• cerrar la sesión (also correct; sounds a bit more “literal”) But cerrar sesión is extremely standard in Spain for logging out.

They’re different actions:

• cerrar sesión = log out / sign out (end the current login session)
• cerrar la cuenta = close the account (terminate the account permanently) A learner might confuse them because English “close” overlaps, but in Spanish they’re clearly distinct.

Rule of thumb:

• antes de + infinitive when the subject is the same (you log out, you shut down)
  • antes de apagar el portátil
• antes de que + subjunctive when the subject changes or is explicit/contrasted
  • antes de que (él) apague el portátil Both can be grammatical, but antes de + infinitive is the natural choice here.

They mean different things:

• apagar el portátil = turn off/shut down the laptop (power off)
• cerrar el portátil = close the laptop (lid) (physically close it) Spanish is more specific here, so apagar matches “powering down.”

Yes. In Spain, un portátil is the everyday word for a laptop. You can also hear:

• ordenador portátil (more explicit)
• portátil (most common in casual speech) Contrast: ordenador = computer (often desktop unless specified).

portátil is stressed on -tíl (the last syllable), and the accent mark shows that irregular stress. Without the accent, Spanish stress rules would place stress earlier, so the written accent is necessary.

Yes. Both are correct but slightly different in emphasis:

• Es importante que cierres sesión antes de apagar el portátil. (straightforward)
• Lo importante es que cierres sesión… (more contrastive/emphatic: “the key thing is…”) Using Lo importante often implies “among all considerations, this is the main one.”

Often yes, if the subject is understood and general:

• Lo importante es cerrar sesión antes de apagar el portátil. That version sounds slightly more like a general guideline/instruction.
  Lo importante es que cierres… feels a bit more direct and personal (aimed at “you”).