С балкона вечером хорошо видно звёзды.

well

Breakdown of С балкона вечером хорошо видно звёзды.

• вечером: in the evening
• балкон: the balcony
• с: from

Questions & Answers about С балкона вечером хорошо видно звёзды.

Why is it с балкона and not из балкона or от балкона or на балконе?

In Russian different prepositions express different spatial ideas:

• 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.