Converting grid resolution from degrees to kilometers
Assuming spherical shape, Earth's circumference is about $40,000\mathrm{km}$. These are split into $360^\circ$, so one degree is a bit more than $100\mathrm{km}$. This is true for latitudes. For longitudes, the circles of constant latitude are shorter as you move away from the equator. Therefore you need to multiply that number by $\cos(latitude)$. To summarize, if $R_e$ is Earth's radius, we got

$$\Delta y=2\pi R_e\frac{\Delta lat}{360^\circ}$$

and

$$\Delta x=2\pi R_e\cos(lat)\frac{\Delta lon}{360^\circ}.$$
Note that here I am using $\Delta x$ and $\Delta y$ for the resolution in a cartesian frame with $y$ pointing south-north and $x$ pointing west-east. For your numbers, think about it as around $50\mathrm{km}$ resolution.