Where did you get the formula from - surely that would tell you what the terms mean, but it looks like that formula simply calculates the height (y) given the vertical distance (x). If you have a known horizontal velocity then you need to use that to calculate your horizontal distance at each step -> distance = velocity * time, and then use the formula to calculate your new y (assuming you know what a, h & k mean).
I don't think (but I am not an expert) that the formula you gave is a generic formula for a parabola that you can use in all cases - such as starting velocity, height above ground etc. The formula though is similar to (but not the same as) the formula defining a parabola where the "top" is at point h,k - as given here http://en.wikipedia.org/wiki/Parabola, but i think it is not similar enough to be close to being correct.
If I was doing this -I would write a loop which work it out as follows :
# where vvo is the vertical velocity at the stat of the jump time slice, and a is the acceleration (normally due to gravity), and t is the amount of time since the last iteration.
x1 = x0 + hv * t # x0 is the horizontal position at the stat of the jump, and hv is the horizontal velocity - it never changes.
y1 = y0 + vv + 0.5 * a * t * t # y0 is the vertical position at the start of the jump, vv is the vertical velocity at the start of the jump, a is the accleration (gravity)
# Draw and swap
move sprite to x1,y1
Loop to the top