if 0x1 goto @done
applymovement 0x1 @mom
msgbox @alert 0x6
applymovement 0x1 @go
msgbox @mom1 0x6
= MOM: [player]!
= You were supposed to be meeting\nPROFESSOR OAK outside so you could\lget your first POKEMON!\lGet out there so you're not\lkeeping him waiting any longer!
It means your flag is already set. There is a good chance that low number flags like 0x2B are in use by the game just to keep track of stuff. I found a list of safe flags once, but since I can't remember them all, I do know that all of the flags in the 1000's are safe and will work just fine.
As you probably already know, "if 0x1" means the if the flag is set, go to @done. "If 0x0" means if the flag is not set, go to wherever the pointer goes. So, if it checks the flag and it is set (0x1) but your script only says what to do if not set (If 0x0...) the script will just continue.