This edition is written in English. However, there is a running Spanish thesaurus at the bottom of each page for the more difficult English words highlighted in the text.
From Wikipedia:
Uncle Vanya (Russian: Дядя Ваня – Dyadya Vanya) is a tragicomedy by the Russian playwright Anton Chekhov published in 1899.
Uncle Vanya is thematically preoccupied with what might sentimentally be called the wasted life, and a survey of the characters and their respective miseries will make this clear. Admittedly, however, it remains somewhat difficult to organize these concepts into a coherent theme as they belong more to the play's "nastroenie," its melancholic mood or atmosphere, than to a distinct program of ideas.