Tool axis controls the orientation of the tool axis relative to the part that is used to create the turning toolpath.
This page contains the following:
User Defined — Select this option to manually specify the tool axis. This option is deselected by default.
Holder angle — Specify the angle of the holder in the X-Z plane. If the angle is set to 0 the holder aligns parallel to the Z axis. If the angle is set to 90 the holder aligns parallel to the X axis.
Tool orientation — Specify the orientation of the holder: