Grounding represents whether and to what extent both feet are grounded. Near the maximum value, both feet are in contact with the ground, and near the minimum value, both legs are far from the ground with a large extent equals to jump and small extent equals to walk. Specifically, a peak value of 0.7 corresponds to actions like jumping, 0.9 to  actions like walking or running. 

To calculate the frame length, count the total number of frames in the dataset. Each frame represents a data point collected over time. The total frame length gives the duration of the motion or activity being analyzed. In this dataset, the total frame length is determined by the number of entries in the data array.