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That is a button on your router/modem for easy wireless setup. It may have a symbol of two curved arrows or a wireless icon or WPS written on it. Not all routers/modem have that button. If you don't see a WPS button on your router or modem, then you have to setup the printer using Standard Setup.
On the computer screen, click Other Setup button (in installation screen if you are running it) and select Standard setup and follow onscreen instructions.
Or follow the steps below to setup wireless using Standard Setup on printer itself.
On the printer screen, go to Setup and select WLAN Setup. Select Standard Setup. From the resulting screen, select your WiFi network, enter password ***** save it. This will connect it to your WiFi network. Then continue setting up the printer by following instructions on the computer.
Refer this article --> https://support.usa.canon.com/kb/index?page=content&id=ART164598
If you have any difficulty on following the steps above, please let me know and I will continue to help you