Learn Hardcore Russian: Если я прихожу домой очень голодный, мама быстро готовит ужин, и через час я уже сытый. - If I come home very hungry, Mom quickly cooks dinner, and an hour later I am already full.

Here, Если я прихожу домой очень голодный, мама быстро готовит ужин means Whenever / If I (normally) come home hungry, Mom (normally) cooks quickly.

If you described a one-time future situation, you’d use the future (often perfective):

Если я приду домой очень голодным, мама быстро приготовит ужин.
If I come home very hungry (on that occasion), Mom will quickly cook dinner.

What is the difference between если and когда here? Could we say Когда я прихожу домой…?

Both если and когда are possible, but they feel different:

Если = if, introduces a condition; it sounds like “in case I come home hungry, this is what happens.”
Когда = when / whenever, introduces a time; it sounds more like a straight description of routine: “When(ever) I come home hungry, Mom cooks quickly.”

So:

Если я прихожу домой очень голодный… – slightly more conditional, like setting up a scenario.
Когда я прихожу домой очень голодный… – a bit more like a neutral statement of habit.

Both are grammatical; context and nuance decide which feels better.

Why is it прихожу and not приду or something with ехать?

Прихожу is the present tense, imperfective of приходить (to come on foot, repeatedly / in general).

Key distinctions:

приходить / прийти – to come (on foot)
- Я прихожу домой в шесть. – I (usually) come home at six.
- Я приду домой в шесть. – I will come home at six (one specific time).
ездить / ехать / приехать / приезжать – to go/come by transport.

In this sentence, we are talking about a repeated, habitual action, so we use:

imperfective: приходить
present tense: я прихожу

Why is it домой and not дом or дома?

These three forms mean different things:

домой – to home, direction towards home
- Я прихожу домой. – I come (to) home.
дома – at home, location
- Я дома. – I am at home.
дом – house / home as a noun (usually with a preposition or verb)
- Я вижу дом. – I see a house.
- Я иду в дом. – I go into the house.

With a verb of motion like прихожу, to express “I come home”, you normally say прихожу домой.

Should it be очень голодный or очень голодным? I often see instrumental after verbs of motion.

Both are possible, but they are not identical:

очень голодный (nominative)
- Feels like two separate facts:
  Если я прихожу домой (и я) очень голодный…
- Very natural in colloquial speech.
очень голодным (instrumental)
- Typical pattern: verb of motion + state in instrumental
- Emphasizes the state in which you arrive:
  Если я прихожу домой очень голодным…
  → If I come home in a very hungry state…

In everyday speech, especially in the present tense and with я, many speakers will just say я прихожу домой очень голодный (nominative) and it is completely acceptable.

What is the difference between голодный and голоден?

Both mean hungry, but they are different forms:

голодный – long-form adjective
- Used attributively: голодный человек – a hungry person
- Also used predicatively in modern, especially colloquial Russian: Я голодный.
голоден – short-form adjective
- Used only predicatively: Я голоден. – I am hungry.
- Sounds a bit more “bookish” or stylistically elevated than я голодный, but both are correct.

In conversation, я голодный is very common and neutral. Я голоден sounds slightly more formal/literary, but also common.

Why is готовит used, not делает or приготовит?

Several points here:

готовить vs делать
- готовить (еду) – specifically to cook / prepare food.
- делать – to do / to make in a very general sense.
  You don’t normally say делать ужин; you say готовить ужин.
готовит vs приготовит
- готовить / готовит – imperfective; describes a process or regular action.
  - Мама быстро готовит ужин. – Mom quickly (habitually) cooks dinner.
- приготовить / приготовит – perfective; focuses on completion / result.
  - Мама быстро приготовит ужин. – Mom will quickly have dinner ready (one-time future result).

In a general habitual sentence like this, готовит is the natural choice.

What is the exact meaning of через час? Why does через mean “in an hour” here?

Через + time period (accusative) usually means “in … (from now)” or “after …”:

через час – in an hour / after an hour
через минуту – in a minute
через три дня – in three days

So и через час я уже сытый = and in an hour I am already full (one hour after she starts / I arrive, the result is that I’m full).

Через also means through / across with places (через дорогу – across the road), but with time expressions it very often corresponds to “in / after” in English.

Why is there no word for “am” in я уже сытый?

Russian normally omits the verb “to be” in the present tense when it is just a copula:

English: I am hungry.
Russian: Я голодный. (not я есть голодный)

So:

я уже сытый literally: I already full
but it means I am already full.

In the past and future, Russian does use the verb быть:

Я был сытый. – I was full.
Я буду сытый. – I will be full.

What exactly does уже add in я уже сытый?

Уже means already and often implies a contrast with an earlier state or with expectations:

я сытый – I am full. (just a fact)
я уже сытый – I am already full (maybe sooner than expected / compared to before).

In this sentence, it contrasts:

beginning: I come home очень голодный
after some time: через час я уже сытый – an hour later the situation has changed; by that time I’m already full.

What is the nuance of сытый? How is it different from words like полный or наелся?

Сытый is the standard adjective for not hungry / full of food:

Я сытый. – I’m full / I’m no longer hungry.

Other related words:

наесться (perfective verb): Я наелся. – I have eaten enough / I’m full (focus on the completed action of eating enough).
полный – full in other senses (a full glass, or “overweight” as an adjective for a person), not “not hungry”.

So for the contrast with голодный, сытый is the natural choice:

голодный → сытый – hungry → full (of food).