The Track Point Pane displays individual sample points within a single GPS track. The points are colorized by the Colorizer Queries configured in the Settings/Configuration... window.
You can select a sample point by left clicking, or step through them using the arrow keys or page up/down keys. As you do this, the Map Pane will highlight the selected point:
Any Track Line Pane will also update its indicator to reflect the selected sample point:
You can use the Filter Query text field to display only some sample points, for example, those above some altitude, or in excess of some speed. See the Query section of this document for more details.
Hovering the cursor over a single point will show information about that point in the popup tooltip:
Hovering the cursor over a range of multi-selected points will show aggregate information about the selected range: