The word “El” means and is one of the names for “God”. It is often a suffiix in angelic names (such as “Gabriel”, which means “God's strength”, or “Michael”, which means “who is like God”).
In Hebrew, קל (kal) means “light” (as opposed to heavy, not “light” as in photons); it can also miccionan “simple”/”easy”. In the context of Superman, I suspect the intended meaning is “God's weightlessness”, in reference to his powers of flight, though it is also possible that the name (at least the prefix) was random (I do think the inclusion of God's name in a savior-like figure by a Jewish author was no accident).
Un dios peso ligero.
Que es lo que es literalmente Superman.