He was a philologist and translator, who became 25 years ago member of the Real Academia Española de la Lengua. As far as I know, he started translating from German (Gertrud von Le Fort), later he translated also from Latin, Greek, Portuguese, Italian and French. His edition of Aristotle's Metaphysics is still the best one in Spanish.
Funny thing is that, being an ultra catholic who even worked for Franco's censorship, he translated one of those books praised by ultra Catholics: Charles Moeller's Littérature du XXe siècle et christianisme. As it happens, the book gained big interest in the conservative sphere because Moeller was the only one reading and commenting forbidden authors. García Yebra's translation of the book was read both by Catholics as well as by non-Catholics because that was the only access to forbidden literature in Franco's Spain.
El Blog de la Redacción de Letras Libres publica hoy una notita necrológica.