Beamforming is a technique that focuses a wireless signal towards a specific receiving device, rather than having the signal spread in all directions from a broadcast antenna, as it normally would. The resulting more direct connection is faster and more reliable than it would be without beamforming.
Although the principles of beamforming have been known since the 1940s, in recent years beamforming technologies have introduced incremental improvements in Wi-Fi networking. Today, beamforming is crucial to the 5G networks that are just beginning to roll out.
Thanks to Josh Fruhlinger (see source)