Terminal velocity is the point at which the drag on a falling object equals the force of gravity pulling it down, so it stops accelerating and falls at a constant speed. For a skydiver this is not a fixed figure — it is whatever the current body position produces.
The trade-off between area and speed
More surface area presented to the airflow means more drag and a lower terminal velocity. A jumper spread wide belly-to-earth falls around 120 mph; the same jumper in a head-down position with limbs tucked presents far less area and falls considerably faster.
This is why freefly disciplines and belly formations rarely mix in the same airspace: the speed difference between groups is a genuine hazard, and drop zones separate them on the load for that reason.
It changes with altitude too
Air is thinner higher up, so there is less drag and terminal velocity is higher. The same body position falls faster at 13,000 feet than at 4,000 feet. High-altitude jumps take this considerably further and require supplemental oxygen.
These pages explain what things are so the language makes sense. They are not instruction and cannot substitute for it — skydiving is taught in person by rated instructors at a drop zone, and anything involving equipment handling or emergency procedures belongs there rather than on a web page.