So How to see saved WiFi passwords in macOS? Open the Keychain Access App. This app stores all the passwords across all the devices that are connected via a single iCloud account.
You can open it by Cmd + Space and then type Keychain Access.
There are a few sections in Keychain Sections. They are login, iCloud, System, System Roots. Tap on System to see the saved Wifi Passwords.
In the list, find the Wifi connection that you want to know the password of. Right Click on the one and Choose Get Info.
In the window that appears, the last option has a checkbox called show password.
Just remember that to see the password, You will have to enter the administrator name and password. Type it in.
Enter the password and click Allow.
As you can see, the password is visible now.