The ancient Christian prayer Ave Maria derives mostly from texts found in the Gospel of Luke. In particular, in Luke 1:28 (Vulgata), we find:
Et ingressus angelus ad eam dixit: Ave gratia plena: Dominus tecum: benedicta tu in mulieribus.
Let us focus on the first part of the salute, Ave gratia plena. The original (?) Greek uses the words Χαῖρε, κεχαριτωμένη which seem to mean "Greetings, [you] favored with grace". This is consistent with the Latin, as well as with the English version of the Ave Maria (the latter being "Hail Mary, full of grace").
However, when it comes to Spanish, things look different. The greeting is instead "Dios te salve María, llena eres de gracia". So, instead of using an equivalent to ave or "hail", it uses "Dios te salve", which translates as Salvet te Deus, or "May God save you". This looks so different from the "original Greek/Latin". Moreover, the "official" (Vatican) Spanish translation of the Gospel of Luke for such verse doesn't greatly differ from the Greek/Latin and English versions:
El Angel entró en su casa y la saludó, diciendo: «¡Alégrate!, llena de gracia, el Señor está contigo».
Alégrate means "rejoice". In any case, it doesn't have anything like "may God save you".
What can explain the difference between the Spanish translation and the Greek/Latin versions?
PS: It might be interesting to notice that the Portuguese and Italian versions use ave, whereas the French uses an entirely different formula to all of the above, namely "Je vous salue Marie" (I salute you, Mary). It would be interesting to compare with more languages, but my knowledge stops there.