Hi Arsen. When you export sensor data in Driving Scenario Designer, the detection data is saved in the workspace. In the Object Detection's Measurement parameter 6 values are returned.
The first three values, as you rightly mentioned, are x,y and z coordinates and the 3 values following them are the respective velocities along the x, y and z directions.
Hope this resolves your doubt.
Here are a few resources to help you understand the object detection output format better.
