“How long does it take to recover from radiation therapy?”

Can’t predict. Too many variables to consider. Ask your radiation therapist.

That is variable and depends on your location and extent of your tumor, your age and your overall underlying health in addition to the condition requiring radiation. It also depends on your regimen and how intensely and/or repeatedly your tumor is irradiated. You can’t expect days to weeks.
I hope this helps and wish you all the best.