At night, you can see more stars there than in Tokyo.
Literal
Night [topic-は], there [at-では] Tokyo [than-より] many stars [subj-が] are-visible.
Two topics stacked: 夜は (night, as topic) and そこでは (there, as topic-contrasted location). Then the comparative 東京より (more than Tokyo) and the predicate 見える ('visible'). Note the comma after 夜は — a subtle cue that the topic has a scope-setting role independent of the rest.