Center velocity represents the speed of movement of the center of gravity of the body. Near the maximum value, the faster the center of the body moves, the closer to the minimum value, the slower the center of the body moves. Specifically, a peak value of 1 corresponds to actions like jumping, 0.6 to jumps within specific actions like ballet jumps or cartwheels, 0.4 to sitting, and 0.2 to walking. 

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.