Plots for 2s orbital are
 

X,Y and Z are respectively

Y will be definitely '$\mathrm{\psi }$' because value of $\mathrm{\psi }$ cannot be negative, thus X will be ${\mathrm{\psi }}^2$ and Z will be $4{\mathrm{\pi r}}^2{\mathrm{\psi }}^2$.
Z represents radial probability function; its value will be zero at origin.