It is a unipolar switch. This means that it turns on and off only when the South pole of the magnet passes by its branded side. The North pole has no effect on it, unless it approaches from the back side of the Hall IC.
This Hall effect IC has a built in voltage regulator with working range from 4.5 to 24V. However, many of the Hall effect switches we sell were tested extensively, and it was found that most of them start working at 3V.