Я перезвоню тебе, когда освобожусь.

I will call you back when I am free.

Breakdown of Я перезвоню тебе, когда освобожусь.

• я: I
• когда: when
• тебе: you
• перезвонить: to call back
• освободиться: to become free

Questions & Answers about Я перезвоню тебе, когда освобожусь.

Why is тебе in the dative case here, not accusative (тебя)?

With the verb перезвонить (to call back), the person you call is typically expressed in the dative: перезвонить кому? → тебе, маме, коллеге.
Using the accusative (перезвонить тебя) is not standard Russian in this meaning.

What exactly does перезвоню mean, and how is it different from позвоню?

Перезвоню = I’ll call you back (a return call, often after missing a call or postponing).
Позвоню = I’ll call you (just making a call; not necessarily “back”).
So перезвоню тебе often implies: “Not now—later.”

Why are both verbs in the future: перезвоню and освобожусь?

Both are perfective verbs, and perfective verbs don’t have a true present tense; their “present forms” refer to the future.
So перезвоню (from перезвонить) is future, and освобожусь (from освободиться) is also future: when I get free / when I’m done.

What does когда освобожусь imply: “when I’m free” or “when I become free”?

Because освобожусь is perfective, it usually means when I become free / once I’m done / when I’m available (after finishing something)—a completed change of state.
If you want more of a “state” meaning, you often use когда буду свободен/свободна = when I am free (available).

Can I say когда освобождаюсь instead?

Когда освобождаюсь (imperfective) is possible, but it tends to sound like:

• a repeated situation: When I’m getting free (usually/regularly), or
• focus on the process, not the moment you become free.
  For a one-time “I’ll call you as soon as I’m done,” когда освобожусь is the natural choice.

Is the comma before когда required?

Yes. In Я перезвоню тебе, когда освобожусь, the когда-clause is a subordinate clause, so Russian normally requires a comma before it.

Can the word order change? For example: Я тебе перезвоню, когда освобожусь or Когда освобожусь, я перезвоню тебе?

Yes, all of these are natural:

• Я перезвоню тебе, когда освобожусь. (neutral)
• Я тебе перезвоню, когда освобожусь. (slightly more conversational; тебе moved earlier)
• Когда освобожусь, я перезвоню тебе. (emphasis on the time condition; the когда-clause is topicalized)
  Meaning stays essentially the same; the focus/flow changes.

Is Я necessary here, or can it be dropped?

It can be dropped if context is clear: Перезвоню тебе, когда освобожусь.
Russian often omits subject pronouns because the verb ending already shows the person.

What verb is освобожусь from, and how is it formed?

It’s from освободиться (perfective, reflexive).
Conjugation (future): освобожусь, освободишься, освободится, освободимся, освободитесь, освободятся.
The -сь is the reflexive marker (a reduced form of -ся used after vowels).

Why is it освобожусь with ж, not освободусь?

That’s a normal stem change in this verb: освободиться → освобожусь.
Some Russian verbs change consonants in certain forms; this one uses -ж- in the -жусь/-жешься pattern.

How would I make it formal/polite?

Use вам instead of тебе:

• Я перезвоню вам, когда освобожусь.
  That switches to the polite you (plural form used for one person).

What’s the natural pronunciation/stress in this sentence?

Typical stresses:

• Я перезвонЮ тебЕ, когдА освобождУсь.
  In fast speech, тебе may sound like т’иб’е, and когда like кагдА.