What Does This Do?
Who's On My Wifi is a Network Monitoring System.
A good analogy is a Home Security System.
At home, most people use locks on their doors to keep away the bad guys. Some people also choose to use a Home Security System to monitor the doors while they're away because locks can be broken and locks don't tell you when they've failed to keep out the bad guys.
This is similar to a Computer Network.
Most people use Wireless Encryption on their network to keep away the bad guys. Some people also choose to use Who's On My Wifi to monitor the network while they're away because Wireless Encryption can be broken and most routers don't tell you when they've failed to keep out intruders.
The analogy isn't perfect because we don't call the police or anything like that on an intrusion, but the software notifies you and gives you some options for protecting your network if it finds an intruder.
So, this is what Who's On My Wifi does.
It sits on a computer that is always on.
It scans your network every 5 minutes looking for intruders.
And if it finds an intruder, it notifies you about it so you can take measures to protect your network.