As first spotted by Thurrott, the initial bits of a thus-far undocumented feature designed to speed up the Bluetooth connection process have started to show up in Windows 10 Redstone 4 preview builds.
The feature would work in much the same manner as recent implementations we've seen with Apple's AirPods, or Android's Fast Pair. Rather than pressing or holding buttons to connect a new device, quick pair would allow you to simply hold a Bluetooth near your Windows machine to pair. Windows 10 would then automatically show a toast notification asking if you'd like to pair the device.
According to Thurrott, Microsoft's take on quick pair appears to rely on the same Bluetooth Classic and Bluetooth LTE functionality as AirPods and Android Fast Pair. At the moment, it's unclear if that means Microsoft's implementation might work with a range of Bluetooth devices.