The 'Skills' abilities determine how many skills you can learn, and how many action points that higher level skills cost to use.
Okay, so...does putting 2 points in hydro mean I get two hydro skills to start with. If I put 1, I get only 1 skill? I guess I'm confused at what the benefit is of putting more than one point in an elemental skill ability. If there's no benefit at all, then I will use the 2 pts elsewhere.