It means exactly what it says. Another device on your local network is using the same IP as your computer. You should be able to change the IP of your PC in your router settings. Look up how to access those and have a mess about with it.

You can find the IP address of your computer using the cmd by typing "ipconfig". If you then go to your router page and find the device that is sharing the same ip, you could instead change that one to something different.

As you can see here, i can assign a different IP address to the device. Yours should be similar to this.