The Uno R4 WiFi has two serial interfaces
The one named Serial communicates with the PC using the USB cable plugged into the R4. It is used to upload code and to interact with the Serial monitor in the IDE
The other one, named Serial1, uses pins 0 and 1 of the R4 to communicate with devices, such as a GPS, attached to those pins.
To use Serial1 just refer to it by its name as you would Serial. For instance, Serial1.begin(115200); Serial1.read(); etc
I don't know whether a special version of SoftwareSerial is needed for the R4, but I expect it would be
On a regular Uno you cannot sensibly use 2 instances of SoftwareSerial