The tool axis is will be tilted from the tilt axis towards the surface normal. The tilt axis can be the X, Y and Z axis or any line created in the geometry. Imaging that tilt axis and surface normal span a plane. Only on this plane the tool can tilt.
The tool axis is tilted 15 degrees towards the main Z axis.
Fixed tilt angle
This angle value describes how much the tool axis direction should be tilted from the defined tilt axis direction. In other words, imagine a plane spanned by the surface normal and the tilt axis. The tool direction vector will rotate on this plane from the tilt axis direction to the surface normal direction about the fixed tilt angle.
Tool axis crosses tilt axis
If the switch tool axis crosses tilt axis is set to true, then it is enforced, that extension of the tool axis direction is intersecting with the defined tilt axis.
Reverse tool
If this switch is set to true, then the tool direction is reversed. E.g. if reverse tool is set to false, then the outer of cylinder is machined. If reverse tool is set to true, then the inner of cylinder is machined.