Left arm extremity angular velocity represents the angular velocity value of left arm. Near the maximum value, the larger the angular velocity value of left arm, indicating fast rotation, near the minimum value, the slower the rotation. 

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.