Adding a title to an axis clarifies what is charted along that axis. The title or the annotation along the axis can also be rotated.
Adding an Axis Title
Use the axis Text property to add a title to an axis. To remove the title, delete the text from the Text property.
Rotating Axis Title
Use the Rotation property to rotate the axis title to 90, 180, or 270 degrees. The 90 and 270-degree rotations are most efficient for vertical axes. To modify the rotation for the X-Axis labels at design time, expand the Axis->X-> Labels->AxisLabelStyle and set the Rotation property.