Assuming you would like to see who is currently connected to your network, there are a few ways to do this.
If you're using a Windows computer, you can open the Command Prompt and type in the command netstat. This will show you a list of all the current connections to your computer, both incoming and outgoing. The first column shows the IP address of the computer that's connected to yours, and the second column shows the port that's being used.
If you're using a Mac, the process is similar. Open the Terminal and type in the command netstat -an | grep LISTEN. This will show you a list of all the current connections to your computer, both incoming and outgoing. The first column shows the IP address of the computer that's connected to yours, and the second column shows the port that's being used.
You can also check to see who is currently connected to your router. The process for this varies depending on what type of router you have, but you can usually access this information by typing your router's IP address into a web browser. From there, you should be able to find the page that shows all the devices that are currently connected to your network.