As x approaches 0 from the positive end, y approached infinity. Since we cannot sub in 0 directly, you just sub in a very small number like 0.01
y = 1/(0.01)^2 = 1/[1/100]^2 = 100^2 = very big
\lim_{x\rightarrow 0^+} \frac{1}{x^2} = \infty
As x approaches infinity, y would get really small...