The PTS and the live servers are totally separate. You will be able to play your characters after the character copy but it will have no effect on the live server.
PATS - Positively Against Acronyms that don't make Sense
You'll have 2 choices in PTS. From the character creation screen you can do 2 things.
The first is to select the 'Template' option at the top left of the screen. Before it was Dragon Bones PTS Template, so now im guessing it'll be 'Summerset PTS Template'. That'll start you off at max level with a bunch of gear in your inventory, including different food, mount upgrades, overland/dungeon armor sets etc.
The second option is to start a new character, (again, top left option should be 'Default' or something similar. That'll start you off just as if you started a new character on the live server
Also, sometimes they move your existing characters over to the PTS, although idk if they're doing that again with Summerset
So when you start on the PTS: you can play your characters (it swaps between NA and EU server characters sometimes) OR you can create a new character and level it up OR you can create a "Template" character which will give you a CP 720 character with all the gear/supplies you can get in the game.
When you leave the PTS, you get nothing. Nothing transfers over to your Live characters.
So its a great way to test certain builds or content with current characters - like if you are struggling with VMA and want to know if that weapon is really worth it- but nothing carries over to Live.