Yes, you can freeze cannabis, but there are some important considerations to keep in mind...

Simple steps :

1 Before freezing, make sure the cannabis is properly dried and cured as excess moisture can lead to mold growth during freezing
2 Place the dried cannabis in airtight, vacuum-sealed bags or containers
3 Freeze cannabis in smaller manageable portions
4 Maintain a consistent temperature in your freezer as fluctuating temperatures can cause trichomes (the resinous glands containing cannabinoids) to become brittle and break
5 If you're planning to store cannabis for an extended period, consider using a deep freeze with a constant temperature of around -18°C (0°F)

And offfcourse avoid handling the cannabis excessively while it's frozen as trichomes can become brittle

*edit* The opinions in the cannabis world are divided when it comes to freezing, but i know many people who do and are satisfied with the outcome