If the wavelength of light is 600 nm

Speed of light  v = 3 $ \times 10^8 $ m/s
Wavelength $\lambda = 600 \ \text{nm} = 600 \times 10^{-9} \ \text{m}$

Formula:
$v = \lambda \nu$

Frequency,
$\nu = \dfrac{v}{\lambda}$

$\nu = \dfrac{3 \times 10^8}{600 \times 10^{-9}}$

$\nu = \dfrac{3 \times 10^8}{6 \times 10^{-7}}$

$\nu = 0.5 \times 10^{15}$

$\nu = 5 \times 10^{14} \ \text{Hz}$

Answer: $5 \times 10^{14} $ Hz