Learn Hardcore Russian: С балкона вечером хорошо видно звёзды. - From the balcony in the evening, the stars are clearly visible.

с + Genitive (с балкона) = from (the surface / from a higher point).
You stand on the balcony and look from it at something lower or farther: с крыши, с горы, со стола.
из + Genitive (из балкона) = from the inside of something. A balcony is an open platform, not a closed space, so из балкона sounds wrong.
от + Genitive (от балкона) = away from, at some distance from. That would mean “from (the area near) the balcony”, not “looking out from the balcony”.
на + Prepositional (на балконе) = “on the balcony” (location), not “from the balcony” (viewpoint).

So с балкона is used because we’re talking about the vantage point you’re looking from.

What grammatical form is балкона?

Балкона is genitive singular of балкон.

The genitive is required because the preposition с (in the sense “from a surface / from on top of”) always takes the genitive:

с балкона, с крыши, с пятого этажа, с дерева.

What exactly is вечером, and why not something like в вечер?

Вечером is the instrumental singular of вечер, used adverbially to mean “in the evening / in the evenings (on a particular evening or generally)”.

Russian very often uses the instrumental as an adverbial of time in set expressions:

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

You do not say в вечер in this meaning. If you want a habitual sense, you can also say по вечерам = “in the evenings (regularly)”.

What part of speech is хорошо here, and what does it modify?

Хорошо is an adverb meaning “well” or “clearly” here.

It modifies видно, describing how something is visible:

видно – “it is visible / one can see (it)”
хорошо видно – “it is clearly / well visible, you can see it well”.

So in English: С балкона вечером хорошо видно звёзды ≈ “From the balcony in the evening, you can see the stars well.”

What is видно exactly? Is it a verb? Why isn’t there a subject like “it”?

Видно is a special predicative form (historically a short passive participle) used in impersonal sentences. It functions like “is visible” in English, but without any grammatical subject.

So:

Вечером видно звёзды. – “In the evening, (the) stars are visible / you can see the stars.”
There is no explicit “it” in Russian; the sentence is built without a subject.

These “impersonal” constructions are very common in Russian for weather, states, and perception:

Темнеет. – “It’s getting dark.”
Слышно музыку. – “You can hear music.”
Было видно город. – “The city could be seen.”

Is звёзды the subject or the object here? What case is it in?

Formally, звёзды is nominative plural in shape, but in sentences with видно you can interpret it either as:

A kind of logical subject (“the stars are visible”), or
A direct object of an impersonal predicate (“it is visible [=one can see] the stars”).

In practice, learners can think of the pattern as:

видно + (Accusative) thing ≈ “you can see X”
e.g. видно машины, видно горы

With звёзды, nominative and accusative plural look the same, so you don’t see a difference in form.

There is also a different nuance if you say видно звёзд (genitive plural): that tends to mean “you can see some stars / an unspecified number of stars” (partitive), while видно звёзды sounds more like “the stars (as a group) are visible.”

What is the difference between хорошо видно звёзды and хорошо видны звёзды?

Both are grammatical but slightly different in structure and nuance:

С балкона вечером хорошо видно звёзды.
- видно = impersonal predicate “is visible / one can see”.
- Focus is on the fact of visibility: “From the balcony in the evening, you can see the stars well.”
С балкона вечером хорошо видны звёзды.
- видны is the short plural form of the adjective/participle видный → “visible”.
- Now звёзды is clearly the grammatical subject of the sentence: “From the balcony in the evening, the stars are clearly visible.”

Meaning is very close, but:

видно sounds a bit more like a general statement of perception.
видны sounds a bit more descriptive of the stars themselves as “being visible.”

Can we omit хорошо and just say С балкона вечером видно звёзды?

Yes, that is perfectly correct:

С балкона вечером видно звёзды. – “From the balcony in the evening, you can see the stars.”

Without хорошо, the sentence is neutral; it just states that the stars are visible.
With хорошо, it adds an evaluative nuance that the visibility is good/clear:

хорошо видно звёзды = “you can see the stars well / clearly.”

How flexible is the word order? Can we move the words around?

Russian word order is relatively flexible, but there are “more natural” versions. Some acceptable variants:

Вечером с балкона хорошо видно звёзды.
Вечером хорошо видно звёзды с балкона. (slightly heavier at the end, but ok)
Звёзды хорошо видно вечером с балкона. (emphasis on звёзды)

What you generally avoid is splitting хорошо видно in a strange way or putting too many modifiers between them, and you keep the sentence flow natural.

The original С балкона вечером хорошо видно звёзды is very typical and neutral in style.

Could we say их хорошо видно instead of хорошо видно звёзды?

Yes, if the stars were already mentioned, you could replace звёзды with the pronoun их:

Звёзды уже взошли. С балкона вечером их хорошо видно.
“The stars have already risen. From the balcony in the evening you can see them well.”

But if you are introducing the stars for the first time, you normally name them rather than use a pronoun:

С балкона вечером хорошо видно звёзды. – natural as a complete statement on its own.

How is звёзды pronounced, and why do I sometimes see it written as звезды?

Звёзды is pronounced approximately like zvYÓZ-dy:

Stress on звёз-.
The ё is always stressed and pronounced yo.

In modern Russian typography, ё is often printed as е (so you see звезды), but the correct pronunciation still has ё. Good dictionaries always mark ё explicitly.

So:

Written carefully: звёзды
Often printed: звезды
Pronounced: [звёзды].

Should there be any commas in С балкона вечером хорошо видно звёзды?

No, there should be no commas in this sentence.

С балкона вечером – a prepositional phrase + an adverbial time phrase; they form one block of adverbial modifiers.
хорошо видно звёзды – the predicate and its complement.

There is no clause boundary or item in a list that would require a comma, so the sentence is written as one continuous string without commas.

How would the meaning change if we said С балкона вечером можно увидеть звёзды instead?

С балкона вечером можно увидеть звёзды is also correct but slightly different:

можно увидеть = “it is possible to see / one can (manage to) see”.
увидеть (perfective) implies the act of noticing/spotting the stars at least once.

Nuance:

хорошо видно звёзды – describes a state of visibility: standing there, the stars are clearly visible.
можно увидеть звёзды – emphasizes possibility / opportunity to see them (e.g. “If you go onto the balcony in the evening, you can see stars”).