This element is shown in the submenu of "Automatic media download", so it is understood that if the word "Nothing" ("Nada" in Spanish) is written under one category (either "When using mobile data", "When connected on Wi-Fi" or "When roaming"), no media content will be downloaded when using that type of connection.
The current translation exceeds more than three times the characters shown in the English version. I think that there is no need for that.

"Desactivada" means "Deactivate", which is not at all what the English text says. "Ningúna" means "none" which acts more naturally as a response to the question of "what media should be downloaded when roaming?"