Physical activity is characterized by any movement produced by muscular contractions that leads to an energy expenditure higher than the resting expenditure. Physical activity does not necessarily mean playing a sport, or completing an intense workout. Simply walking for 30 minutes a day, for example, is considered a regular physical activity proven to yield numerous health benefits.
The activity value you can see in the Biovotion App indicates the intensity of your motion (activity). The higher the activity value the higher the intensity of your motion.
Source: Withings Research Institute