There is no neutral or brake safety switch on the engine itself; those are added by the equipment manufacturer (e.g., zero-turn mower). At the engine level, the starter will engage any time the blue wire receives 12V.
Most standard Predator 670 harnesses follow these color conventions, though it is always recommended to verify with a multimeter before making permanent connections:
The Predator 670 uses a standardized small-engine color code. Note: Harbor Freight may vary batches, but the following is standard.