To use this webpage, simply type your name or nickname in the first text box, and then it will produce a bunch of different fonts that you can copy and paste into your display name / username area in the PUBG app.
It generates special characters by converting your regular characters into Unicode characters that look similar to your input characters. It's not actually showing you different "fonts" (like "Comic Sans", "Arial", "Times New Roman", etc.), but is instead showing you just your browser's normal default font, but with a bunch of new characters that look like a separate font. They just seem like new fonts because you don't see these characters very often - they're not on your keyboard.
There are over one hundred thousand different characters/symbols, but your keyboard can only hold about 100 of them, so this generator is just a helper to convert your regular keyboard characters into some fancy ones that look like normal alphabet characters, but they're slightly different in some way.
Most of these fonts should work for PUBG (PlayerUnknown's Battlegrounds), and you can actually use them for many other games too. Often games tend to have "clans" which use specific combinations of characters in their names - often involving special symbols and fancy fonts like those that you get if you use this webpage. In any case, I hope you find some of these PUBG fonts useful! Using special characters is a fun way to add a bit of personality to your character, and it can also help you stand out from the crowd a bit! :)