The device can record light levels from 0 to 83,000 lux. In Europe, a really bright summer day in full sunlight might exceed this level, but typically the maximum light level will be 60-80,000 lux.
The light meter is accurate to ±2%. To ensure accurate readings, make sure the device isn’t shaded and isn’t placed immediately under a light source. Consider installing several devices in the environment to get a good average reading across the area.