Learn Hardcore Russian: Естественно, я хочу отдохнуть вечером. - Naturally, I want to rest in the evening.

In this sentence, though, it functions more like an introductory word (parenthetical), very similar to “of course”, “naturally”, or “obviously” in English:

Естественно, я хочу отдохнуть вечером.
→ Naturally / Of course, I want to rest in the evening.

Grammatically, естественно is an adverb, but in this position (set off by a comma at the start of the sentence) it behaves as a sentence adverb or discourse marker, commenting on the whole statement.

Why is there a comma after Естественно?

The comma is there because Естественно is used as an introductory word (вводное слово).

Russian often sets off words like:

конечно (of course)
естественно (naturally)
разумеется (certainly)
к счастью (fortunately)
по-моему (in my opinion)

with commas when they comment on the whole sentence rather than modify a single verb or adjective.

So:

Естественно, я хочу отдохнуть вечером.
Here Естественно = Naturally / Of course (comment on the whole statement) → comma is needed.

But if естественно were a “normal” adverb modifying an adjective or verb, you might not use a comma:

Это выглядело совершенно естественно.
It looked completely natural.
(No comma, because it just means in a natural way.)

Could I say Я естественно хочу отдохнуть вечером instead? How does that change the meaning?

You can say it, but the nuance changes.

Естественно, я хочу отдохнуть вечером.
→ Naturally / Of course, I want to rest in the evening.
Here Естественно is a comment on the whole sentence (introductory word).
Я естественно хочу отдохнуть вечером.
Grammatically possible, but now естественно is heard as a “normal” adverb modifying хочу (I naturally want…).
This sounds odd or at least much less natural in most contexts, because “I naturally want to rest” isn’t something people often say; it feels stylistically awkward.

In real-life speech, Russians almost always prefer the first version with the comma when they mean “of course / naturally” as a reaction or comment:

Естественно, я хочу отдохнуть вечером. – very natural.
Я естественно хочу отдохнуть вечером. – possible, but stylistically strange in everyday speech.

What is the difference between отдохнуть and отдыхать? Why is отдохнуть used here?

Отдыхать and отдохнуть are an aspect pair:

отдыхать – imperfective: to rest, to be resting, to rest regularly
отдохнуть – perfective: to have a rest (as a single, complete event), to get some rest

In this sentence:

я хочу отдохнуть вечером
The speaker wants to have some rest (as a completed action) in the evening.

If you said:

Я хочу отдыхать вечером.

this usually implies:

I want to (generally) spend evenings resting (habit or preference),
or I want to be in a state of resting in the evening.

So:

отдохнуть = to take a rest and finish resting (one episode)
отдыхать = to be resting / to rest as an ongoing or habitual process

In context, wanting to get some rest this evening is naturally expressed with отдохнуть.

What form is отдохнуть exactly? Is it an infinitive? What is its aspect and conjugation?

Отдохнуть is the infinitive form of a perfective verb.

Infinitive: отдохну́ть (perfective)
Paired imperfective: отдыха́ть

Conjugation of отдохнуть (future tense, since perfective doesn’t have a present):

я отдохну́ – I will rest / I’ll have a rest
ты отдохнёшь
он/она/оно отдохнёт
мы отдохнём
вы отдохнёте
они отдохну́т

In я хочу отдохнуть, the verb remains in the infinitive because it follows хочу (I want to …), just like English “want to rest”.

Why is it вечером and not something like в вечер or этот вечер?

Вечером is the standard, very common way to say “in the evening” or “this evening / tonight” in Russian.

Grammatically:

вечером is the instrumental case of вечер (evening), but here it functions as an adverbial: in the evening.

Typical patterns:

утром – in the morning
днём – in the daytime / in the afternoon
вечером – in the evening
ночью – at night

You don’t normally say в вечер for “in the evening” in Russian. That sounds wrong/foreign.

If you really want to stress “this particular evening”, you might say:

этим вечером – this evening
сегодня вечером – this evening / tonight (today evening)

But вечером alone usually already implies “this evening / tonight” in the right context:

Я хочу отдохнуть вечером.
I want to rest this evening / in the evening.

Does вечером mean “this evening” specifically, or “in the evenings” generally?

Вечером on its own is somewhat flexible and can mean either:

This evening / tonight (one specific time)
– especially if said about plans for today:
- Я хочу отдохнуть вечером.
  I want to rest this evening.
In the evenings (generally / habitually)
– in a more habitual or descriptive context:
- Обычно я работаю днём, а отдыхаю вечером.
  I usually work in the daytime and rest in the evenings.

Context decides the meaning. In your sentence, it’s most naturally understood as “this evening”, especially if the conversation is about today’s plans.

How would I say “Of course I don’t want to rest in the evening” using this structure?

You just negate хочу:

Естественно, я не хочу отдыхать вечером.
– Naturally, I don’t want to rest in the evening (in general / as a habit).
Естественно, я не хочу отдохнуть вечером.
– Naturally, I don’t want to have a rest this evening (this specific evening).

Both are grammatically correct; choose отдохнуть vs отдыхать depending on whether you mean one specific evening or evenings in general.

Is this sentence formal, informal, or neutral? Are there more common alternatives to Естественно?

The sentence is neutral and perfectly fine in both spoken and written language. It’s not slangy or overly formal.

Common alternatives to Естественно with slightly different vibes:

Конечно, я хочу отдохнуть вечером.
Very common, friendly, neutral. → Of course…
Разумеется, я хочу отдохнуть вечером.
A bit more formal/elevated. → Certainly, of course…
Само собой, я хочу отдохнуть вечером.
Colloquial, conversational. → Obviously, naturally…

Естественно is fully natural, but конечно is probably the most frequent everyday option.

How do you pronounce each word and where is the stress: Естественно, я хочу отдохнуть вечером?

Approximate stresses (marked with ´):

Есте́ственно – ye-stést-ve-na
Stress on the second syllable: сте́.
The initial Е is [йиэ]/[йиэ̆], roughly ye.
я – ya (short, unstressed here in comparison to surrounding words)
хочу́ – ha-CHÚ
Stress on the second syllable: чу́.
The final у is stressed and pronounced clearly.
отдохну́ть – at-dakh-NÚT’
Stress on the last syllable: ну́ть.
Double дх is [дх] or slightly [дх]/[тх]-like, with voiced–voiceless assimilation.
ве́чером – VE-che-ram
Stress on the first syllable: ве́.

So, with stress indicated:

Есте́ственно, я хочу́ отдохну́ть ве́чером.

Does the verb change depending on whether the speaker is male or female?

No. In this sentence, all the verbs are in forms that do not show gender:

хочу – 1st person singular, present tense
отдохнуть – infinitive

Russian verbs show gender only in certain forms (e.g., past tense singular, short-form adjectives, some participles). For example:

Я отдохну́л. – I (male) rested.
Я отдохну́ла. – I (female) rested.

But я хочу отдохнуть вечером is the same for both male and female speakers.

Can I move вечером to another place in the sentence? For example, Естественно, вечером я хочу отдохнуть?

Yes, Russian word order is fairly flexible, and all of these are possible with slightly different emphasis:

Естественно, я хочу отдохнуть вечером.
Neutral: main focus on the fact of wanting to rest; вечером just specifies when.
Естественно, вечером я хочу отдохнуть.
Extra emphasis on вечером – It’s in the evening that I want to rest (not at some other time).
Вечером, естественно, я хочу отдохнуть.
Stronger focus on вечером as the topic: As for the evening, naturally I want to rest.

All are grammatical; the original version is the most straightforward and neutral.