Voi opri televizorul înainte de culcare.

It is the future tense, first person singular: I will turn off.

Romanian often forms the standard future with:

voi, vei, va, vom, veți, vor + infinitive

So here:

• voi = future auxiliary for I
• opri = infinitive of a opri = to stop / to turn off

So voi opri means I will turn off.

It looks the same, but here it is not the pronoun.

In this sentence, voi is the future auxiliary meaning will for I. Romanian often leaves out the subject pronoun, so:

• Voi opri televizorul = I will turn off the TV
• Eu voi opri televizorul = also I will turn off the TV, with eu added for emphasis

So in this sentence, voi does not mean you (plural).

Because after the future auxiliary voi, Romanian uses the infinitive.

• a opri = to turn off / to stop
• voi opri = I will turn off
• opresc = I turn off / I am turning off

So:

• opresc televizorul = I turn off the TV / I’m turning off the TV
• voi opri televizorul = I will turn off the TV

Because Romanian usually puts the definite article at the end of the noun.

• televizor = a TV / television
• televizorul = the TV / the television

So -ul is the equivalent of English the.

In this sentence, televizorul means a specific TV, just like the TV in English.

Yes. Its basic meaning is to stop, but with machines, devices, lights, TVs, engines, etc., it often means to turn off.

For example:

• a opri televizorul = to turn off the TV
• a opri lumina = to turn off the light
• a opri mașina = to stop the car

So in this sentence, opri is naturally understood as turn off.

Literally, it means something like before going to bed or before sleep.

Breakdown:

• înainte de = before
• culcare = a noun related to a se culca, which means to go to bed / lie down

So înainte de culcare is a very natural Romanian expression for before bed or before going to bed.

Because înainte normally uses de when it is followed by a noun or noun phrase.

So:

• înainte de culcare = before going to bed
• înainte de cină = before dinner
• înainte de examen = before the exam

This is just the normal pattern: înainte de + noun.

Yes. That is also correct and natural.

Compare:

• Voi opri televizorul înainte de culcare.
• Voi opri televizorul înainte să mă culc.

The difference is mainly in structure:

• înainte de culcare uses a noun phrase
• înainte să mă culc uses a clause meaning before I go to bed

Both are common.

It is correct and perfectly natural, especially in neutral or standard Romanian.

In everyday speech, many people also use:

• O să opresc televizorul înainte de culcare.
• Am să opresc televizorul înainte de culcare.

These also mean I will turn off the TV before going to bed.

So your sentence is good Romanian; it just uses the standard voi + infinitive future.

Yes. Romanian word order is fairly flexible.

You can also say:

• Înainte de culcare, voi opri televizorul.

That puts a little more focus on before going to bed.

The original sentence, Voi opri televizorul înainte de culcare, is also completely natural.