Cool find.
The ‘SPB’ at the top of the dated side is for ‘St. Petersburg’ in Russia. The other letters will likely be for the owner/manufacturer. On the other side, I can’t make out much but the letters will likely be in the Russian cyrillic alphabet and relate to things like the inspection and quality of the packaged consignment.
The vast majority of these early Russian seals are from bales of flax or sacks of flax seed in varying qualities, but they were also used for things like consignments of hemp, herring and timber.