What does this mean?

車窓から山が見えた。

It means from 列車 right, not a car window?

There's no way we can know, since the word can mean either a car or train window. You need to provide context for your questions.

車窓 (しゃそう) is car [train] window.

I could see a mountain from a car[train]'s window.

EDIT: yudantaiteki beat me to it and then beat me to my edit - he obviously is correct.

Actually it's more often train window than car window.

Inny Jan Wrote:車窓 (しゃそう) is car window.

I could see a mountain from a car's window.

Except the entire first page of google image matches is pictures out of train windows..

[Zgarbas]

The window of the vehicle you are in?

しゃ‐そう【車窓】‐サウ
列車•電車•自動車などの窓。

So, as others are saying.