Newbie Schrodinger equation question

I discovered physics at a later age and am trying to learn more about Schrodinger's equation, here it is in one dimension -- gotta crawl before you walk, I guess -- http://scienceworld.wolfram.com/physics/SchroedingerEquation.html == my question is the variable that is multiplied by i x h bar -- I do not know what the meaning is of the greek letter attached to psi in the numerator and t in the denominator. Thank you for your time.