Tur-bo is a spell which allows the user to create whirlwinds and manipulate them at whatever use they want. It can also make things twirl instead of creating a tornado to twirl things.
In The Final Battle: Part 1, Gwen used a small Tur-bo to blow a gas-like spray out of Kevin's breathing area. Gwen later used Tur-bo on Negative Swampfire's attack, reversing the attack that he threw at her.
In The Ultimate Enemy: Part 2, Gwen used Tur-bo to save Kevin from the Esoterica.
Turbo means "whirling motion" and "whirlwind" in Latin.