"Beaming" is a Zwave feature that is designed to increase battery life for door locks.
Like most battery-operated Zwave devices, battery-operated locks sleep most of the time and just wake up occasionally to see if there are any messages. This conserves battery. However, people waiting at the door for a lock to open need a very quick response.
Z wave introduced beaming to address this. A nearby mains-powered device, typically a wired wall switch or plug-in pocket socket, will keep repeating the same message to the lock until it is received. So it is the wired device that is using power. This ensures that as soon as the lock wakes up to check, The message will be available.
Only the neighbor closest to the lock needs to support beaming.
If a Zwave lock can be locked and unlocked by the SmartThings mobile app, but the status is often shown as "unknown," or if lock requests are not always performed, placing a beaming repeater close to the lock often corrects the situation.
The official Conformance Statement for the device at the Z-wave Alliance products website will indicate whether a specific model supports beaming or not.
If you add a new repeating device, or physically relocate an existing one, run the Z-wave repair utility so that all your devices will update their neighbor tables to use the new repeater. It can take a while for all the individual tables to get updated, so you may not see improvement until the next day.
Zigbee locks having difficulty communicating to the hub do not need beaming repeaters, but may still benefit from a zigbee repeater placed closer to the lock.
See Repeaters for more information and specific models that support beaming.