Fast BSS Transition is a method for a device to seamlessly move move between Basic Service Set (BSS) AKA a Wireless AP’s, inside of an Extended Service Set (ESS) AKA, WLAN deployment.
This can help prevent Voip calls from dropping while someone is walking across campus or between buildings.
FT PSK is a Password option for Cisco equipment The idea is
Some more resources for learning more.
https://evanmccann.net/blog/2021/11/unifi-advanced-wi-fi-settings
https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/80211r-ft/b-80211r-dg.html