The circle has radius $1$ (it passes through $N(1,0)$). Point $P$ is at angle $\frac{\pi}{3} = 60^\circ$ from the positive $x$-axis, so its coordinates are $(\cos 60^\circ, \sin 60^\circ)$. $y\text{-coordinate} = \sin 60^\circ = \frac{\sqrt{3}}{2}$