That is for two devices that are both connected to the same network. If I understand what this program is doing (without actually trying it), it allows two devices to directly connect to one another via Wi-Fi to transfer a file.
With KDE Connect, to send a file from Device A to Device B, your file travels from Device A to a network router (and any number of network switches, etc. in between), then from the router to Device B. It has to make several hops across a number of devices to reach its destination. And both endpoints have to be connected to the same external network.
With this program, Device A and Device B create a direct Wi-Fi connection to each other and just send the file. One hop. Two devices. Direct. The devices are establishing their own ad-hoc Wi-Fi connection for the purpose of the file transfer.