The graph geometry window show angles, distances and areas for the currently active graph (which is displayed in the Digitize toolbar).
At each point, the angle is defined between the line from the previous point, and the line to the next point.
At each point, the distance is defined as the length of the line to the next point.
The functional area of the curve is the area calculated by integrating the area under the curve. The polygonal area of the curve is the area within the polygon through all of the points in the curve.
Until the coordinates are defined by axes points or a scale bar, the graph geometry window will show information in the screen coordinates, which are in units of pixels. Afterwards, the geometry measurements are in the graph coordinates.