Я выключаю телефон, чтобы лучше сосредоточиться.

Выключаю is the imperfective verb form, and here it usually suggests:

• a habitual action: I turn off my phone
• or an action seen as a process: I am turning off my phone

Выключу is perfective future, so it would mean I will turn off my phone as a single completed action.

So:

• Я выключаю телефон, чтобы лучше сосредоточиться.
  = I turn off my phone / I’m turning off my phone to concentrate better.
• Я выключу телефон, чтобы лучше сосредоточиться.
  = I will turn off my phone to concentrate better.

Yes. In Russian, the present tense of an imperfective verb can often cover both meanings.

So Я выключаю телефон can mean:

• I turn off my phone (habitually, as a general practice)
• I am turning off my phone (right now)

The exact meaning depends on context.

For example:

• If someone asks what you usually do before studying, it sounds habitual.
• If someone sees you doing it now, it sounds like right now.

It is in the accusative case, because it is the direct object of выключаю.

You are turning off what?
→ телефон

So:

• Я = subject
• выключаю = verb
• телефон = direct object in the accusative

Because телефон is:

• masculine
• singular
• inanimate

For masculine inanimate nouns, the accusative singular is the same as the nominative singular.

So:

• nominative: телефон
• accusative: телефон

Compare that with an animate noun:

• Я вижу брата
  Here брат becomes брата in the accusative because it is animate.

Чтобы introduces a purpose clause. Here it means:

• so that
• in order to

So:

• Я выключаю телефон, чтобы лучше сосредоточиться.
• I turn off my phone in order to concentrate better.

It connects the main action (turning off the phone) with the goal (concentrating better).

Because after чтобы, Russian often uses the infinitive when the subject is the same in both parts of the sentence.

Here, the same person does both actions:

• I turn off the phone
• I concentrate

So Russian naturally says:

• Я выключаю телефон, чтобы лучше сосредоточиться.

If the subject changes, Russian usually uses a different structure, for example:

• Я выключаю телефон, чтобы дети могли сосредоточиться.
  = I turn off the phone so that the children can concentrate.

Сосредоточиться is perfective, and that makes sense here because the sentence focuses on the result: becoming properly focused.

With purpose clauses, Russian often prefers a perfective infinitive when the goal is to achieve a result.

So:

• сосредоточиться = to become focused / to manage to focus
• imperfective forms like сосредотачиваться would emphasize the ongoing process more

In this sentence, the idea is:
I turn off my phone so that I can focus better — that result is what matters.

-ся is a reflexive ending, but it does not always translate literally as myself.

In this verb, сосредоточиться simply means to concentrate / to focus. It is just the normal dictionary form of the verb.

So although historically it is reflexive in form, in modern usage you should learn it as a whole verb:

• сосредоточиться = to concentrate
• сосредотачиваться = to be concentrating / to concentrate habitually

Because лучше is an adverb here, not an adjective.

It modifies the verb сосредоточиться:

• сосредоточиться как?
  лучше = better

So it means to concentrate better.

Compare:

• лучше = better (adverb/comparative)
• лучший = better/best as an adjective, used with nouns
  Example: лучший способ = the best way

No, Russian word order is fairly flexible.

The original sentence is natural:

• Я выключаю телефон, чтобы лучше сосредоточиться.

But you could also say:

• Чтобы лучше сосредоточиться, я выключаю телефон.

This version puts more emphasis on the purpose first:
To concentrate better, I turn off my phone.

Both are correct; the difference is mainly one of focus and style.

Yes, often you can.

Russian often drops subject pronouns when the meaning is clear from the verb ending.

So you can say:

• Выключаю телефон, чтобы лучше сосредоточиться.

This still clearly means I turn off / I’m turning off the phone to concentrate better.

Including Я can add:

• clarity
• emphasis
• contrast

For example:

• Я выключаю телефон, а он нет.
  = I turn off my phone, but he doesn’t.

Yes, very normal.

Выключать / выключить means to turn off / switch off.

Common examples:

• выключить телефон = turn off the phone
• выключить свет = turn off the light
• выключить компьютер = turn off the computer

You may also hear отключить телефон, but that usually suggests disconnecting or cutting something off, and it is less neutral for this exact everyday meaning.

The main stresses are:

• Я выключа́ю телефо́н, что́бы лу́чше сосредото́читься.

A rough pronunciation guide:

• выключа́ю = vyk-lyu-CHA-yu
• телефо́н = ty-lye-FON
• что́бы = SHTOH-by
• лу́чше = LOOCH-she
• сосредото́читься = sa-srye-da-TOH-chi-tsa

The чтобы is pronounced with шт, not as it is spelled letter by letter.

Not exactly.

Выключаю телефон specifically means I turn off the phone.

If you want to say I silence my phone or put my phone on silent, Russian would usually use a different expression, such as:

• Я ставлю телефон на беззвучный режим.
• Я включаю беззвучный режим.

So выключаю is stronger: the phone is being switched off, not just muted.