Team Switzerland is Bella's team. It's her way of declaring herself neutral. She loves Edward and Jacob, and she's not going to pick sides. Switzerland was a neutral country in WWI, and so Bella is neutral when it comes to Edward and Jacob's feud. Team Switzerland is for those who love both Edward and Jacob, and don't care who Bella chooses to be with because they love them both.
"When it comes to all this enemies nonsense, I'm out. I am a neutral country. I am Switzerland." -Bella to Edward, Eclipse, pg. 143
Bell used Switzerland, because this country try to maintain peace and not jump on someone's side, so Bella said in this way that she love them both and dosen't want to choose between them. I think, it's like that