The Measure section of the tab allows for the measurement from point on the map to another. This option will effectively draw a special line onto the map allowing for the distance to be calculated when the mouse is hovered over it. To draw a measure line, select the Measure option from within the tab and then click on the first point on the map, then select any further vertices before finishing the line drawing by Double-clicking at the end point.

The Clear Measures option will remove any measure lines from the mapping interface.