Wi-Fi Protected Setup (WPS) is a standardized WiFi technology enabling a WiFi connection without knowing the password. See more information here.
Not all routers or WiFi devices support WPS (for example - iOS devices do not, but Android device do).
However, if both your router and device support WPS - it's the simplest and quickest way to get connected.
(If your router or device do not support WPS - you would have to recover your WiFi password)
Position the device you wish to connect (e.g., phone, laptop, tablet) close to your home WiFi router - no more than 3-5 ft away, if possible.
If you cannot move your device - a large Smart TV, for example - don't worry. Just make sure you have a good and stable WiFi signal where your device is located (you can check that by placing a mobile phone next to your device's location with the app in "fasTest loop" mode).
Locate your home WiFi router's WPS push button
The button may be located in the front, top, back or sides of the router - and sometime marked with this