What Does Kief Press Mean?
A kief press, also known as a pollen press, is a device used to compress the powdered trichomes (small, hair-like projections from the flower bud) of cannabis flowers (or other medicinal plants), known as kief or pollen into a solid form, known as hash (or hashish). These solids are alternatively referred to as “cakes”, “disks”, or “pucks”.
Kief presses are also used as a method for readily combining different blends of cannabis strains.
Maximum Yield Explains Kief Press

Kief presses are generally simple devices. There is a chamber where the kief is inserted, a solid end cap, and an end with a plunger or auger-like press attached. The pollen is compacted by the press to the desired levels and is generally allowed to sit in the press for a few hours to retain its form.
Kief presses are used for a variety of reasons. The foremost being that the kief has a much higher concentration of THC levels, making for a more intense high for the user, and the press makes the utilization of the hash easier.
Once pressed, the potency of the kief can be preserved for quite a while. It is also used as a storage method as the disks are easier both to store and conceal that the loose, powder-like kief. As a practical matter, compressed kief will also not as easily blow away or get lost like powdered kief can.