Через час я вернусь домой и выключу телефон.

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Breakdown of Через час я вернусь домой и выключу телефон.

• и: and
• домой: home
• через: in

Questions & Answers about Через час я вернусь домой и выключу телефон.

Why does через час mean in an hour, and what case is час in here?

Через + accusative expresses a time interval from now: через час = after an hour / in an hour (i.e., one hour from the present moment).
Here час is accusative singular (it looks the same as nominative for this masculine inanimate noun: час).

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How would I say in one hour vs in two/three/five hours with через?

You still use через + accusative, but the noun changes with numbers:

• через один час
• через два / три / четыре часа
• через пять / шесть / семь часов
  So: number + the correct form of час.

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What does вернусь mean grammatically, and why is it the future tense?

Вернусь is the 1st person singular future of the perfective verb вернуться (to return).
Perfective verbs in Russian form the simple future (one word) to mean a completed action in the future: I will return (and be back).

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Why is вернуться reflexive (ending in ), and what’s the difference between and ?