Your basic understanding of traction is quite accurate. But the use of traction has been modified and updated as technology has improved and as our understanding of the use of traction has changed.
First, traction may be sustained (held steady) or intermittent (on and off in a repeated cycle). It may be applied manually (the therapist distracts and holds the body part) or by motorized means (on a mechanized table). The force applied may be considered a distraction or traction. Distraction tells us the therapist is attempting to use the force at a specific level or area of the spine. Traction is more of a general dispersion of the force throughout the spine.
Traction can be applied with the patient in many different positions. You may be lying on your back, face down, suspended upright, or even inverted (upside down). Sometimes a special table is used to put the patient’s spine in a specific posture. These tables are split with the upper portion stable and the lower portion adjustable. No harness is needed when using a split table because the force is provided by the body posture or motion of the table.
It sounds like you are in good hands. Finding a therapist who understands how traction works and who doesn’t just apply the same type of traction to all patients is important. However, you may want to ask your therapist more about what she meant and what is intended for future sessions.