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:
The Return of the Native is Thomas Hardy's sixth published novel. It first appeared in the serial Belgravia, a publication known for its sensationalism, and was presented in twelve monthly installments from January to December of 1878. Due to the novel's controversial themes, Hardy had some difficulty finding a publisher; reviews, however, though somewhat mixed, were generally positive. In the twentieth century, The Return of the Native became one of Hardy's most popular novels.