That means the IP is assigned to your ethernet interface, not the wifi.
If all you did was setup a wifi connection, and didn't apply an IP to the wifi interface, you aren't done yet.
The simplest thing might be to unplug the ethernet, and the restart the computer.
Don't plug the ethernet in. Connect with the wifi. Check for IP.
I'm guessing you won't see an IP, or you'll see self-assigned (169.x.x.x).
You need to connect, and then assign an ip, gateway, and route to the wifi interface.