I am new to Zorin and I have basic knowledge, I want to know that if I enable firewall without setting any rules then I am safe?

Those are safe, not sure if they will work. From gufw configuration GUI, you can hit the rules tab and the remove icon on the bottom to remove the rules that you select in the window. Once they are removed, open a terminal with ctl+alt+t and enter in each of these: sudo ufw allow 1714:1764/udp …