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:
Mary Lennox is a sickly, sour-faced little girl born in India to wealthy British parents who have very little interest in her, leaving her in the care of an Ayah from birth. Orphaned by an outbreak of cholera, she is sent back to England to the legal guardianship of her only remaining relative: her father's brother-in-law, Archibald Craven, a reclusive widower.