Learn Hardcore Russian: В парке я иногда вижу семь-восемь друзей вместе. - In the park I sometimes see seven or eight friends together.

Starting with В парке focuses on the place: In the park, I sometimes see...
Starting with Иногда emphasizes frequency: Sometimes I see...
Keeping я close to вижу is a more “neutral” pattern: Я иногда вижу...

The basic meaning stays the same, but Russian commonly puts what is already known or background at the beginning and the new or emphasized information toward the end.

What does the hyphen in семь-восемь mean? Why not just семь или восемь?

Семь-восемь with a hyphen expresses an approximate range, like “seven to eight” or “about seven or eight”.

семь-восемь друзей ≈ seven or eight friends, roughly
семь или восемь друзей = either seven or eight friends (more like a strict “or”)

In everyday speech, семь-восемь feels more natural and less precise, like English “seven or eight friends” said loosely.

Why is it друзей and not друзья?

Two reasons: case after the verb and how numbers work in Russian.

Case with the verb:
- Вижу кого? → see whom?
  The direct object is in the accusative case.
- For animate plural nouns, the accusative plural = genitive plural.
- So we need the genitive plural form of друг: друзей.
Numbers 5 and up: With numbers 5, 6, 7, 8... in the nominative or accusative, the noun is in genitive plural:
- пять друзей
- шесть друзей
- семь друзей
- восемь друзей

So with семь-восемь, we also use генитив множественного числа (genitive plural): друзей, not друзья.

What case is друзей, exactly?

Друзей is genitive plural:

Singular: друг (nominative), друга (genitive)
Plural:
- друзья – nominative plural
- друзей – genitive plural

In this sentence, друзей is:

grammatically accusative plural (object of вижу),
but for animate plural nouns, the accusative plural form looks like the genitive plural form.

So друзей is the correct form both because of the verb (вижу кого?) and the numeral (семь-восемь).

Why is the verb вижу and not something else? What infinitive does it come from?

Вижу is 1st person singular, present tense of the verb видеть (to see).

Infinitive: видеть (imperfective)
я вижу
ты видишь
он / она / оно видит
мы видим
вы видите
они видят

We use видеть / вижу for general, repeated, or ongoing perception, which fits with иногда (sometimes).

A perfective counterpart would be увидеть (to see once / to catch sight of), e.g.:

Иногда я увижу там старого друга.
From time to time I happen to see an old friend there (occasionally, once in a while).

But for regular, habitual “I sometimes see…”, the imperfective вижу is standard.

What is the difference between видеть and смотреть? Could I say я иногда смотрю семь-восемь друзей?

No, я иногда смотрю семь-восемь друзей is wrong in this context.

видеть = to see (passive perception: things come into your field of vision)
смотреть = to look (at), to watch (active, you direct your attention/eyes)

You видите someone simply by happening to see them:

Я иногда вижу друзей в парке.
I sometimes see friends in the park.

You смотрите на someone if you intentionally look at them:

Я иногда смотрю на друзей, как они играют.
I sometimes look at my friends as they play.

So this sentence correctly uses вижу.

Can иногда go in other places in the sentence?

Yes. Иногда (sometimes) is quite mobile:

В парке я иногда вижу семь-восемь друзей вместе.
В парке я вижу иногда семь-восемь друзей вместе.
Иногда в парке я вижу семь-восемь друзей вместе.
Я иногда вижу в парке семь-восемь друзей вместе.

They are all acceptable. The most natural/common ones are:

Иногда я вижу в парке семь-восемь друзей вместе.
В парке я иногда вижу семь-восемь друзей вместе.

Moving иногда slightly shifts rhythm or emphasis, but doesn’t change the basic meaning.

What does вместе add? Isn’t it obvious that friends are together?

Вместе literally means together.

семь-восемь друзей = seven or eight friends (could be separate, scattered)
семь-восемь друзей вместе = seven or eight friends together as a group

In context, вместе tells you they are all in one group, not just that you happen to see seven or eight friends individually somewhere in the park at different times or places.

You can drop вместе if you don’t care whether they are grouped, but then the sentence is slightly less specific.

There is no word for “the” or “a” in В парке. How do I know if it’s “in a park” or “in the park”?

Russian has no articles (no a/an/the), so В парке can mean:

in a park
in the park

Which one you choose in English depends on context, for example:

If you’re talking about a particular park you both know, you’d translate it as “in the park”.
If this is the first time the park is mentioned and it’s not specific, “in a park” might fit.

The Russian sentence itself stays the same: В парке я иногда вижу семь-восемь друзей вместе.

If in English I usually say “my friends”, why is there no “my” in семь-восемь друзей?

Russian often omits possessive pronouns (мой, твой, наш, etc.) when it’s obvious from context whose thing/person it is.

In this sentence:

семь-восемь друзей will very often be understood as “seven or eight (of my) friends” if you’re talking about your own social life.
Adding моих is possible:
В парке я иногда вижу семь-восемь моих друзей вместе.
This makes “my” explicit, but can sound slightly heavier and more emphatic.

So:

семь-восемь друзей – usually enough; “my” is implied by context.
семь-восемь моих друзей – “seven or eight of my friends”, with extra emphasis on they are mine.

Why is the first word written as В (capital) here, but normally the preposition в is lowercase?

This is just orthography, not grammar.

At the beginning of a sentence, the first letter is capitalized in Russian, whatever the word is: В.
As a preposition in the middle of a sentence, it’s normally lowercase: в парке.

So В парке here is only capitalized because it’s the first word in the sentence, not for any grammatical reason.