Сегодня вечером я выключу телефон и пойду спать пораньше.

Russian word order is flexible, and putting Сегодня вечером first sets the time frame right away: As for tonight...

This is very natural in Russian. You could also say:

• Я сегодня вечером выключу телефон и пойду спать пораньше.

That means the same thing, but the original version sounds slightly more natural if you want to emphasize when this will happen.

Вечером is the instrumental case of вечер.

In Russian, the instrumental is often used in time expressions like:

• утром = in the morning
• днём = in the daytime / during the day
• вечером = in the evening
• ночью = at night

So сегодня вечером literally means something like today, in the evening, but in natural English it is just this evening / tonight.

Выключу is future tense, while выключаю is present tense.

• выключаю = I am turning off / I turn off
• выключу = I will turn off

Since the sentence is about something the speaker plans to do later, Russian needs the future:

• Сегодня вечером я выключу телефон... = Tonight I will turn off my phone...

Also, выключить is a perfective verb, so its future is formed with one word: выключу.

This is about aspect.

Russian has two main verb aspects:

• imperfective: ongoing, repeated, or process-focused
• perfective: completed, single-result action

Выключить is perfective, so its future is a simple future:

• я выключу = I will turn off

If you used the imperfective выключать, the future would be:

• я буду выключать

But that would mean something more like I will be turning off or suggest repeated/process meaning, which does not fit here.

In this sentence, the speaker means a single completed action: I’ll turn off the phone.

Пойду is future: I will go.

• иду спать = I am going to bed / I’m off to sleep now
• пойду спать = I will go to bed

Since the sentence talks about a future plan for this evening, пойду is the right choice.

Also, пойти often means to set off / to go and do something, so пойду спать is a very common way to say I’ll go to bed.

That is simply a normal Russian expression. Russian often uses:

• идти / пойти + infinitive

to mean go and do something.

Examples:

• пойду есть = I’ll go eat
• пойду читать = I’ll go read
• пойду спать = I’ll go to bed / I’ll go sleep

English usually says go to bed, while Russian often says go sleep. That is just a difference in idiom.

Пораньше means earlier or a bit earlier than usual.

It comes from раньше = earlier, with the prefix по-, which often softens the meaning and gives the sense of somewhat / a little.

So:

• лягу пораньше = I’ll go to bed a bit earlier
• приду пораньше = I’ll come a bit earlier

In this sentence, пойду спать пораньше means I’ll go to bed early / a bit earlier than usual.

Russian often leaves out possessive words like my, your, and his when they are obvious from context.

Here, if someone says:

• Я выключу телефон

it is naturally understood as I’ll turn off my phone, unless context suggests another phone.

Russian does this much more often than English. Adding мой is possible, but it usually sounds emphatic or contrastive:

• Я выключу мой телефон, а не твой. = I’ll turn off my phone, not yours.

Телефон is the direct object of выключу, so it is in the accusative case.

But for inanimate masculine singular nouns, the accusative looks exactly the same as the nominative.

So:

• nominative: телефон
• accusative: телефон

That is why there is no visible change.

If it were an animate masculine noun, you would see a different form more often.

Because both actions have the same subject: я.

Russian, like English, does not need to repeat the subject if it is clear:

• Сегодня вечером я выключу телефон и пойду спать пораньше.

This means:

• I will turn off the phone
• and I will go to bed early

Russian could repeat я, but it usually would not unless you wanted special emphasis.

Yes, both are perfective future forms:

• выключу from выключить
• пойду from пойти

Perfective is used because the speaker is talking about two single, completed actions in the future:

1. turning off the phone
2. going to bed

The focus is not on the process, but on the fact that these actions will happen and be completed.

That is why perfective sounds natural here.

Yes, you could, but the nuance is slightly different.

• пойду спать = I’ll go to bed / I’ll go sleep
• лягу спать = I’ll lie down to sleep / I’ll go lie down to sleep

Пойду спать is the broader, very common everyday expression. Лягу спать focuses a bit more on physically lying down.

Both are correct, but пойду спать is especially common in casual speech.

Here и just connects two actions in sequence:

• выключу телефон
• и пойду спать пораньше

So the meaning is:

• I’ll turn off the phone and go to bed early

In context, it also suggests a natural order: first the phone gets turned off, then the speaker goes to bed. Russian does not need an extra word like then, because the sequence is already easy to understand.