f(x) = 4x^3 - 8squarerootx for 0 equal/less x equal/less 10

I've got thus far

y' = 12x^2 - (4/squarerootx)

when y' = 0, x = 0.64439

y'' = 24x + 2x^-1.5

when x = 0.64439, y'' = 19.33, which is a local minimum

y-coordinate of x = 0.64439 is -5.35

Left boundary x = 0, y = 0

Right boundary x = 10, y = 3,974.70

and I know how to draw the graph

okay so what is the global minimum/maximum? What does that mean?