prunning evergreen tree.
These look like mature and nicely shaped Alberta Spruce. They usually don't need pruning.
They are not easy to prune well. The only parts you can remove if needed is under two inches of the newest growth.
Evergreens like these cannot produce new green growth if they are cut back into old, brown/woody areas. If you do, those dark holes will stay.
If you do prune, May/June would be the time.